10 Best Duct Seal Putty Compound (October 2026) Expert Guide

Finding the right duct seal putty compound is essential for maintaining energy efficiency and preventing air leaks in your home or commercial building. A high-quality putty provides a durable, flexible barrier that adapts to various surfaces and conditions without cracking or shrinking over time.

We have carefully evaluated ten leading products based on their formulation, ease of application, durability, and specific use cases ranging from HVAC systems to electrical conduit sealing. Our analysis considers user feedback, material properties, and performance in real-world scenarios to help you make an informed decision.

Each selection in this guide highlights unique strengths and ideal applications to match your specific sealing needs. Please note that product availability and pricing may change frequently, so we recommend checking current listings before making a final purchase decision for your project.

Top 3 Picks for Best Duct Seal Putty Compound

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Top 10 Best Duct Seal Putty Compound in 2026 Compared

This side-by-side comparison highlights the key specifications and features of each product to help you quickly identify the best fit for your specific sealing requirements.

1. RectorSeal Duct Seal 81880 – Best Overall Duct Seal Putty Compound

4.7Editor scoreCheck price on Amazon

RectorSeal Duct Seal 81880 Compound

1 lb gray putty block

Non-corrosive and non-irritant

Paintable immediately after application

Safe for plastic and metal

The RectorSeal Duct Seal 81880 Compound stands out as a top choice for both professionals and DIYers due to its versatile formula and ease of use. With a high rating of 4.7 stars, this product has consistently met expectations for creating air and water-tight seals across various applications including plumbing and electrical conduit.

Pros

• Highly rated by professionals
• Non-toxic and asbestos-free
• Reusable and hand-moldable
• Adheres to most surfaces
• Does not damage plastic

Cons

• May require reapplication over years
• Limited quantity per block

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Its gray, soft, and non-toxic formulation allows for easy hand-molding to any form, making it ideal for irregular gaps around service mast entries and flashings. The compound is resistant to water, alcohol, and mild acids, ensuring long-term durability without corroding metals or damaging plastic materials. It can be painted immediately after application without bleeding through the dry paint film.

While the product is highly effective, some users note that large projects may require multiple blocks since it comes in a 1 lb size. Additionally, while durable, extreme environmental conditions over many years might necessitate occasional inspection and reapplication to maintain optimal sealing performance.

This sealant is best suited for HVAC/R professionals, plumbers, and homeowners looking for a reliable general-purpose sealant. Its safety profile and ability to be reused make it a practical investment for ensuring energy efficiency and protecting against moisture intrusion in residential and commercial settings.

Professional Grade Safety and Durability

Formulated to be non-irritant and asbestos-free, this putty ensures safe handling during installation while providing robust protection against environmental factors.

Versatile Application Range

From electrical conduit ends to metal fabrication joints, this compound adheres to clean dry surfaces and adapts to various sealing needs effectively.

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2. Gardner Bender DS-110N – Best Budget Duct Seal Putty Compound

4.7Editor scoreCheck price on Amazon

Gardner Bender DS-110N Duct Seal Compound

1 pound duct seal compound

Seals conduit openings effectively

Protects terminal boxes and bushings

Deadens switch gear panel noise

The Gardner Bender DS-110N offers an excellent balance of performance and affordability for those seeking a reliable duct seal compound. It is particularly valued by electricians for its ability to seal conduit openings against drafts, dust, moisture, and noise. The dough-like compound is easily thumbed over holes and gaps, facilitating quick and efficient application.

Pros

• Affordable pricing point
• Effective against drafts and dust
• Deadens noise in panels
• Easy to thumb over gaps
• Protects from corrosive elements

Cons

• Less packaging compared to kits
• May be too soft for some

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Its protective qualities extend to terminal boxes, pot heads, and bushings, shielding them from corrosive elements that could otherwise lead to electrical failures. The ability to deaden switch gear panel noise adds an extra layer of utility in industrial or commercial electrical installations where sound reduction is beneficial.

Although it is a budget-friendly option, the product maintains a high rating. Some users might find the consistency softer than other brands, which could affect handling in very warm conditions without proper storage. It is also sold as a single block which may not suffice for large-scale projects without bulk purchasing.

This product is ideal for electricians and homeowners needing a cost-effective solution for sealing electrical entries. Its proven track record and ease of use make it a staple in many toolboxes for maintaining safe and efficient electrical systems.

Electrical Protection and Noise Reduction

This compound not only seals but also protects sensitive electrical components from corrosion and helps reduce operational noise in switchgear panels.

Simple and Direct Application

With no tools required, the dough-like texture allows for immediate application by hand, making it convenient for quick repairs and installations.

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3. Duct Seal Putty Waterproof Mastic Roll – Best Premium Duct Seal Putty Compound

4.8Editor scoreCheck price on Amazon

Duct Seal Putty Waterproof Mastic Roll

5 ft continuous roll design

3/8 inch thick moldable sealer

Weather resistant and durable seal

Cut knead and press application

This Waterproof Sealant Mastic Roll offers a premium solution for sealing air gaps with its continuous roll design. It is designed for HVAC openings, pipe openings, and wall penetrations, providing a professional-looking seal that reduces waste and speeds up installation. Users appreciate the flexibility and durability of the seal which resists weather conditions effectively.

Pros

• Continuous roll reduces waste
• Highest rated in the list
• Weather resistant for outdoors
• Flexible long-lasting seal
• Tool-free application

Cons

• Higher price point than blocks
• Requires storage to keep soft

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The application process is straightforward, requiring users to cut the roll to length, knead it until soft, and press it firmly into gaps. This moldable gap sealer conforms easily to irregular surfaces, creating a secure fit that maintains flexibility over time. It delivers a waterproof barrier that helps block air leaks, moisture, and dust.

While the price is higher than standard blocks, the value comes from the continuous design and higher performance rating. Some users may find the roll format requires careful storage to prevent it from drying out or becoming too stiff if exposed to air for extended periods.

Ideal for both indoor and outdoor applications, this product is perfect for professionals who need a reliable and aesthetically pleasing seal for various penetrations. Its weather-resistant properties make it a robust choice for protecting against the elements.

Professional Finish and Efficiency

The continuous roll design allows for a clean and professional application that minimizes waste and ensures consistent thickness in every application.

Superior Weather Resistance

Designed to withstand various conditions, this sealant maintains its integrity and flexibility even when exposed to outdoor environmental challenges.

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4. Duct Seal Putty 12 Pack – Best Value Kit Duct Seal Putty Compound

4.6Editor scoreCheck price on Amazon

Duct Seal Putty 12 Pack

12 pack 30g each block

Non-hardening flexible sealing putty

Ideal for indoor gap sealing

Moldable for irregular spaces

This 12-pack offers excellent value for homeowners and small businesses tackling multiple sealing tasks around the house. Each block is individually packed to keep unused pieces clean and ready to use. The soft moldable texture easily fills irregular spaces around pipes, wall penetrations, and HVAC openings to help reduce drafts.

Pros

• Value pack for multiple jobs
• Individual packaging reduces waste
• Non-hardening formula
• Blocks drafts effectively
• Easy press and shape

Cons

• Smaller blocks may run out fast
• Indoor use only specified

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The product is designed for indoor gap sealing, making it ideal for kitchens, bathrooms, and utility areas. Its non-hardening formula ensures the putty stays flexible after application without cracking or shrinking, maintaining a reliable seal over time. No tools are required, simplifying the application process.

While the small 30g blocks are convenient for storage, they may not be sufficient for large gaps without using multiple pieces at once. Additionally, it is not intended for plumbing leaks or pressurized water leaks, so users should be clear on its specific use cases.

This set is perfect for DIY enthusiasts who need a versatile tool for small to medium sealing projects. The convenience of the packaging ensures that you always have fresh material available when you encounter a new gap.

Home Comfort Improvement

By effectively sealing gaps around common home spots, this putty helps improve comfort by reducing drafts and enhancing overall energy efficiency.

Convenient Storage and Usage

Individually packed blocks ensure hygiene and prevent the putty from drying out between uses, keeping it ready whenever a seal is needed.

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5. IDEAL Industries 31-601 – Most Versatile Duct Seal Putty Compound

4.7Editor scoreCheck price on Amazon

IDEAL Industries 31-601

1 lb gray putty block

Permanently soft and easy to mold

Multi-surface versatility metal masonry

Air and moisture seal barrier

IDEAL Industries provides a reliable option with their 31-601 duct seal compound which creates a durable barrier that blocks air leaks and moisture. The putty-like consistency stays flexible over time, won't harden, crack, or shrink, making it easy to apply, remove, and rework as needed. It adheres well to metal, masonry, wood, and plastic.

Pros

• Permanently soft formula
• Safe for plastics and metals
• Paintable for clean finish
• Versatile on many surfaces
• Jobsite ready

Cons

• Price varies by seller
• Standard size limit

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The product is formulated to be safe for use around plastics and metals without corroding wiring or damaging surfaces. It is paintable immediately after application for a clean finish, which is suitable for visible installations where aesthetics matter. This weatherproof protection provides reliable performance both indoors and outdoors.

The 1 lb block size offers ample material for multiple projects but might require repurchasing for larger jobs. While generally stable, some users might find it slightly firmer than other options initially, requiring a bit more kneading before application.

This compound is well-suited for electricians and general contractors who need a versatile and safe sealant for various surfaces. Its ability to remain soft permanently ensures that adjustments can be made long after the initial installation without issues.

Multi-Surface Adhesion

With the ability to adhere to a wide range of materials including masonry and metal, this product offers flexibility in diverse construction environments.

Aesthetic and Functional Finish

Being paintable allows for a clean finish that blends with the surroundings, making it a practical choice for areas where visibility is a concern.

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6. Red Devil 0841DX F-Seal 181 – Best Liquid Sealant Duct Seal Putty Compound

4.5Editor scoreCheck price on Amazon

Red Devil 0841DX F-Seal 181

1 gallon fiber reinforced sealant

UL 181 certified for HVAC

Low VOC fast drying formula

Indoor and outdoor durability

Red Devil offers a fiber-reinforced liquid sealant that is distinct from traditional putty but serves similar sealing purposes for HVAC systems. It is UL 181 A-M & B-M certified for use on all types of HVAC ductwork including metal, fiberglass, and flexible ducts. The weather-resistant sealant withstands various conditions for both interior and exterior use.

Pros

• Fiber reinforced formula
• UL certified for HVAC ducts
• Indoor and outdoor durability
• Low VOC low odor
• Exceeds industry standards

Cons

• Liquid not putty format
• Requires brush application

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The fast-drying and low VOC properties ensure quicker application and reduced drying time, making it safer for use in sensitive environments. This product is designed to improve energy efficiency and performance by ensuring leak-free HVAC systems. It surpasses all SMACNA Pressure and Sealing Classes for top-quality performance.

As a liquid, it requires a brush for application which might not be preferred for small gaps compared to putty. It is better suited for sealing joints and seams in ductwork rather than plug sealing holes. Users should ensure surfaces are clean before application for best results.

This sealant is ideal for HVAC professionals looking for a certified liquid solution that offers high durability and compliance with industry standards. Its fiber reinforcement adds strength to the seal making it suitable for demanding conditions.

Industry Certification and Compliance

With UL certification and SMACNA compliance, this product meets rigorous standards for safety and performance in HVAC duct sealing applications.

Efficient Installation Process

The fast-drying nature of the sealant minimizes downtime during installation, allowing systems to be operational sooner than with slower alternatives.

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7. 8 Pack Waterproof Duct Seal Putty – Best Multi-Tasking Duct Seal Putty Compound

4.3Editor scoreCheck price on Amazon

8 Pack Waterproof Duct Seal Putty

8 pack 30g each bag

Multipurpose waterproof hole filler

Cures to rock hard durable seal

Soft flexible for hand molding

This 8-pack is an all-in-one fix for household repairs including walls and duct seals. It is engineered to create an air-tight and waterproof barrier. Once cured, it effectively seals out moisture on any surface. The clay is soft and flexible for easy hand-molding with no tools or mixing required.

Pros

• Versatile repair solution
• Blocks odors effectively
• Cures to rock hard
• No mixing required
• Convenient packaging

Cons

• Requires 3-5 days drying
• Not for damp areas

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It serves as a versatile repair solution for waterproof hole filler, duct seal putty, and even a plumber's putty. It also blocks odors to prevent unwanted smells. However, it requires a full 3-5 days of drying time before exposing it to moisture for maximum effectiveness which is a key consideration for planning.

Users must ensure the surface is clean and dry before application and avoid using it on damp areas. While it cures to a rock-hard seal, this hardening process differs from non-hardening putty. Some users may prefer to test a small area first to ensure the drying time fits their schedule.

This product is suitable for homeowners needing a multipurpose clay for various tasks around the house. Its ability to cure hard makes it great for structural gaps that need a permanent fix rather than a flexible one.

Odor Blocking Properties

Beyond sealing gaps, this putty helps prevent unwanted smells from passing through walls and holes improving indoor air quality and comfort.

Permanent Hardening Seal

Once cured, the putty forms a durable rock-hard barrier that offers long-lasting protection against moisture and air infiltration.

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8. 3-Pack Silicone Putty Non-Hardening – Best Silicone Duct Seal Putty Compound

3.8Editor scoreCheck price on Amazon

3-Pack Silicone Putty Non-Hardening

8.8 oz total weight

Water-resistant gap sealant

Removable and reusable putty

Easy to knead and shape

This 3-pack includes a total of 8.8 oz of silicone sealing putty that stays soft and pliable for shaping and repositioning. It is water-resistant and designed to help reduce the entry of water, air, dust, and moisture. The putty is removable and reusable allowing for adjustments when needed.

Pros

• Non-hardening silicone base
• Reusable and reshaping
• No tools required
• Suitable for many surfaces
• Water-resistant properties

Cons

• Lower rating than others
• Smaller total weight

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Users can easily knead and shape the putty by hand around irregular surfaces. No mixing or curing is required making it a quick solution for maintenance repairs. It is suitable for use around pipes, wall openings, sinks, and cable holes. However, the lower rating suggests some users might have experienced adhesion issues.

While versatile, it may not stick as aggressively as other options which can be a pro or con depending on your needs. The silicone base offers flexibility but may require proper surface preparation for best results. Storage is simple but care should be taken to avoid contamination.

This product is best for users who prioritize flexibility and reusability over permanent bonding. It is a good choice for temporary seals or areas that might need future adjustment without the hassle of scraping or sanding.

Adjustability and Reusability

The non-hardening nature allows users to remove and reshape the putty, offering flexibility for future adjustments without damage to surfaces.

General Maintenance Repairs

Ideal for small tasks around the home such as sealing conduit entries or gaps around bathtubs where a flexible seal is required.

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9. 1 Pack Moldable Silicone Putty Grey Solid Roll – Best Heat Resistant Duct Seal Putty Compound

4.4Editor scoreCheck price on Amazon

1 Pack Moldable Silicone Putty Grey

1.5 foot x 1 inch roll

Flexible and durable bond

Weatherproof and heat resistant

Multi purpose applications versatile

This duct seal putty is a non-hardening multi-purpose gap sealant putty for filling voids and seams. It can be applied to create custom barriers to divert or block liquids. It is designed to be flexible and durable and can be hand molded to any form. It provides a long-lasting reliable bond that won't loosen or peel over time.

Pros

• Heat resistant and waterproof
• Dielectric strength for electrical
• Hand molded to form
• Weatherproof and reliable
• Solid roll format

Cons

• Roll may be bulky
• Single roll size limit

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One of its standout features is its weatherproof and heat-resistant properties which ensure moisture resistance in challenging environments. It has excellent dielectric strength to prevent the passage of electrical current making it suitable for electrical applications. It works on various materials including plastic metal wood and glass.

The solid roll format may be less convenient than blocks for some users due to storage space requirements. Additionally, it is a single roll which may not be sufficient for extensive projects without ordering multiple units. Users should also ensure clean dry surfaces for best adhesion.

This product is ideal for situations requiring heat resistance or electrical insulation alongside sealing capabilities. Its versatility makes it a useful tool for complex projects where standard putty might not withstand extreme temperatures.

Extreme Environment Performance

Designed to perform in extreme temperatures, this putty maintains its seal integrity even when exposed to heat or cold stress.

Electrical Safety Features

With excellent dielectric strength, this putty offers an extra layer of safety for electrical applications by preventing current passage.

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10. Moldable Silicone Putty Plumbers Duct Sealant – Best Reusable Sealant Duct Seal Putty Compound

4.0Editor scoreCheck price on Amazon

Moldable Silicone Putty Plumbers Duct

2 pack moldable silicone putty

Non hardening and reusable

Weatherproof and heat resistant seal

Multi purpose applications versatile

This moldable silicone putty is a non-hardening multi-purpose gap sealant for filling voids and cracks. Unlike regular caulk it stays soft and can be removed and reused again and again. It creates a reliable seal that prevents water penetration and ensures moisture resistance. It comes with 2 rolls of the putty.

Pros

• Reusable after removal
• Heat resistant properties
• Weatherproof sealing
• No messy cleanup needed
• Two rolls included

Cons

• Basic packaging
• Average rating

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The product is easy to apply by hand and can be used on various surfaces including conduit ends and service mast entrances. It is weatherproof and heat-resistant which makes it suitable for challenging environments. The ability to remove and reshape it without scraping offers significant convenience for ongoing maintenance tasks.

However, the rating is average compared to other products which may indicate variability in adhesion or texture. Users should test for their specific application. The two rolls provide a bit more material than single packs but may still require multiple purchases for large projects.

This putty is best for users who value the ability to make mistakes or adjust their seal without permanent commitment. It is a practical choice for dynamic areas where seals may need to be inspected or changed regularly.

Mess-Free Maintenance

The reusable nature of this putty means that adjustments can be made without the need for scraping or sanding, keeping your workspace clean.

Resistant to Challenging Conditions

With weatherproof and heat-resistant qualities, this sealant stands up to environmental stress, providing reliable protection in tough areas.

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Buying Guide – How to Choose the Best Duct Seal Putty Compound

Selecting the right duct seal putty compound depends on several factors including the surface type, environmental conditions, and specific application needs. This guide breaks down the key aspects to consider to help you find the perfect match.

Application Surface Material

Different putties adhere better to different materials. Some are formulated to work safely with plastics while others are designed for metal masonry or wood. Always check the compatibility with the surfaces you are sealing to avoid damage or poor adhesion.

Ensure the product label specifies safe use on your target materials for a long-lasting seal.

Indoor vs Outdoor Use

For outdoor applications you need a sealant that is weather-resistant and can withstand temperature fluctuations without cracking. Indoor putties may be softer and lack the UV protection needed for exterior conditions. Assess where the seal will be located to choose the appropriate durability level.

Opt for weather-resistant formulas for any project exposed to the elements.

Non-Hardening vs. Hardening

Non-hardening putties remain flexible over time making them ideal for areas subject to vibration or movement. Hardening putties provide a more rigid seal which can be useful for structural gaps but may crack if the material shifts. Decide based on whether flexibility or rigidity is more important for your needs.

Choose non-hardening for dynamic joints and hardening for static structural repairs.

Electrical Safety and Dielectric Strength

When sealing electrical conduits ensure the putty has high dielectric strength to prevent electrical current from passing through. Safety certifications and non-corrosive properties are crucial to avoid damaging wiring. This is especially important for professional electrical installations where safety is paramount.

Look for products explicitly rated safe for electrical applications to ensure compliance and safety.

Packaging and Quantity

Products come in blocks rolls or packs of smaller units. Consider the total amount you need and how easy it is to store the product. Individual packaging can reduce waste and keep unused pieces fresh but larger rolls may be more efficient for big projects.

Calculate your total sealing needs to choose a package size that minimizes waste without running out mid-project.

Ease of Application

Some putties require tools or brushes while others can be applied by hand. Consider your comfort level and the complexity of the gaps you are filling. A dough-like texture that molds easily can save time and effort during installation.

Prioritize hand-moldable options for quick repairs and complex shapes.

Price and Value

Cost should be weighed against performance and durability. While budget options are tempting they may require more frequent replacement or offer less durability. Consider the cost per unit of sealing and the reputation of the brand for value.

Invest in a reputable brand to ensure long-term performance and minimize rework.

Specialty Features

Some putties offer additional benefits like odor blocking heat resistance or paintability. Identify if your project requires these extras to enhance the seal's functionality or appearance. For example a paintable sealant might be preferred for visible areas.

Check for specialty features that align with your specific project requirements.

How to Use and Care for Your Duct Seal Putty Compound

First prepare the surface by cleaning and drying it thoroughly to ensure the best adhesion. Remove any dust grease or loose debris that could prevent the putty from sticking properly. Using a dry cloth or mild cleaner can help achieve a clean base for the seal.

Next take a small portion of the putty and knead it in your hands until it softens and becomes pliable. If it is too firm you can warm it slightly by rubbing it between your palms. Once soft press it firmly into the gap or hole shaping it to fill the space completely.

After application allow the putty to set according to the manufacturer's instructions. Most non-hardening putties remain soft and do not require a cure time but some hardening varieties need several days. Store any unused putty in a cool dry place sealed in its packaging to maintain its texture for future use.

Frequently Asked Questions

Is duct seal putty toxic?

Most high-quality duct seal putties are non-toxic and safe for handling. However always check the label for specific safety information. Some products may contain ingredients that require gloves or ventilation. Avoid ingestion and wash hands after use.

Can I paint over duct seal putty?

Many duct seal putties are designed to be paintable immediately after application. Ensure the putty is fully applied and smooth before painting. Some brands specifically state they will not bleed through paint film. Always test a small area first.

Does this putty harden over time?

Non-hardening putties are designed to stay flexible and pliable indefinitely. Hardening varieties will cure to a rock-solid state. Choose the type based on whether you need a flexible or rigid seal for your specific application area.

Can I use it on plumbing pipes?

Some putties are safe for plumbing gaps but not for active water leaks. Always check the product description for water leak warnings. For pressurized water leaks use a dedicated plumbing sealant to avoid potential failure or damage.

How long does it last?

A well-applied putty can last many years without cracking or shrinking. Environmental factors like extreme temperatures or exposure to moisture may reduce its lifespan. Regular inspection can help identify when reapplication is needed.

Does it work for electrical conduits?

Yes many are specifically designed for sealing electrical conduit ends and boxes. They provide a barrier against moisture and dust. Ensure the product is non-corrosive to protect the wiring inside the conduit.

Final Thoughts on Choosing the Best Duct Seal Putty Compound

We have explored ten top-rated duct seal putty compounds suitable for a wide range of applications from electrical conduits to HVAC openings. Each product offers unique benefits whether you need a budget option or a premium flexible seal.

When making your choice prioritize factors like surface compatibility environmental resistance and ease of application. The right product can significantly improve your home's energy efficiency and safety against drafts and moisture intrusion.

Always check current pricing and availability before purchasing as stock levels may change. With the right tools and knowledge you can achieve a professional-quality seal that lasts for years.

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