Frost King R338H Slim 3/8" Foam Weatherstripping, Tool-Free Installation for Intentional, Minimalist Home Upgrades
Frost King R338H Slim 3/8" Foam Weatherstripping, Tool-Free Installation for Intentional, Minimalist Home Upgrades
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Why you'll love it
- Self-stick backing requires no tools, glue, or professional installation
- Wide range of sizes (11 variants from 3/16" to 9/16" thickness) ensures a fit for nearly any gap
- Rubber foam construction delivers both sealing compression and shock absorption in one product
- Multi-surface versatility works on home, auto, and marine applications from a single roll
- Made in USA manufacturing and limited lifetime warranty signal trusted, long-term quality
- Stretches slightly when laid in place to reach the actual advertised length
- Foam compresses nicely but is thick enough to not be crushed
- Adhesive remains strong even after 4+ years on previously purchased rolls
- Blocks drafts effectively even after a month of regular door opening/closing
- Easy to separate from backing paper
- Significantly dampens outside sound on casement windows
Perfect for
- Seal gaps around windows and exterior doors to block drafts and reduce energy bills
- Weatherstrip vehicle doors and trunks to cut down on road noise and rattles
- Weatherproof boat cabins and hatches against water intrusion in marine environments
- Cushion and stabilize appliances, electronics, or cabinet doors to prevent vibration
- Block dust, insects, and cold air from entering through small structural gaps
- Shimming a permanent A/C home filter that is slightly smaller than needed
- Replacing compromised weatherstrip on a 2005-2007 Mustang to fix water leaking onto floorboard
- Sealing lids on ATV/four-wheeler boxes to keep out moisture and dirt
- Preventing wind noise and air leaks around car windows
- Adding a cushion/protective strip that is sticky enough not to move
- Preventing rattling/noise on a window fan by taping where it contacts the window frame
- Sealing plexi panels over old windows without messy caulking
About us
From your basement to your roof, from the front door to the back, Frost King products are there to save you money and save you energy. Frost King, simply the trusted name in home insulation. It all began nearly a century ago when Frost King introduced the nation’s first do-it-yourself weatherstripping kit. That simple kit, just 17 feet of felt carpet strips and some nails, managed to single handedly ignite America’s “Do-It-Yourself” revolution. Since that time, Frost King has expanded to help you save money and energy in just about every corner of your home. During the winter, Frost King products will keep the cold air out, insulate your pipes and protect your rooftops from freezing snow. In the summer, Frost King keeps gutters clean, protects your home from leaks, and cuts air conditioning costs.
Frost King R338H Self-Stick Rubber Foam Weatherseal, 3/8"W, 3/16"T, Black|Blacks
A tough, durable self-stick tape with minimal compression. Use the Rubber Foam Weatherseal as a weatherstrip, or as a gasket or to cushion and stabilize major appliances. Plus, on cars, trucks and boats, it can help prevent rattles, vibrations and squeaks.
Product Information
The product is 3/8x3/16 BLK Foam Tape Easy and simple use kit The product is manufactured in United States Minimum Compression Superior Shock Absorbing Minimum Compression Superior Shock Absorbing Extra tough and durable Seals around windows and doors Many automotive and marine uses Show more
Brand Frost King Material Rubber Color black|Blacks Product Dimensions 120"L x 0.38"W Item Thickness 0.25 Inches Recommended Uses For Product weatherstripping, sealing gaps in vehicles, cushioning and stabilizing appliances UPC 077578012209 Number of Items 1 Manufacturer Frost King Unit Count 10.0 Feet Part Number R338H Item Weight 0.6 ounces Item model number R338H Is Discontinued By Manufacturer No Size 3/8"W, 3/16"T Style 3/8"W, 3/16"T Item Package Quantity 1 Included Components No Batteries Included? No Batteries Required? No Warranty Description Limited Lifetime Warranty
Frequently Asked Questions
Will the self-stick backing keep my window trim looking clean and uncluttered?
Yes, the slim 3/8" profile sits discreetly along the compression edge, and the peel-and-stick installation leaves no visible hardware, caulk lines, or fasteners to disrupt a clean aesthetic.
Does the matte black color blend with my modern black window hardware?
Black blends discreetly with most door, window, and vehicle trim, making it an intentional design choice rather than an eyesore on minimalist interiors with black or dark hardware.
Can I install this without adding bulk to my frameless or thin-profile windows?
Yes, the 3/16" thick foam adds minimal material, and its compressible nature means it disappears into the gap when the window is closed, preserving clean lines and sightlines.
Is the foam a single neutral color that won't clash with my design palette?
The black foam is intentionally neutral and pairs well with most minimalist palettes — white, gray, black, natural wood, and muted tones — without introducing a new color element.
Does the adhesive leave residue that would disrupt a clean interior when removed?
The pressure-sensitive adhesive is designed to bond securely during use but typically removes cleanly from painted trim, making it a low-commitment addition to a curated space.
I follow a less-is-more philosophy — is one product really enough to seal my whole apartment?
Yes, the 10-foot roll covers multiple windows or one full door perimeter, so a single purchase handles most of the weatherstripping needs in a small, intentional living space.
Will the foam stay hidden once installed, or will it be visible on my window frame?
The foam sits in the gap between the sash and frame, so it is essentially invisible when the window is closed, supporting a clutter-free, minimalist look.
Is the installation truly tool-free, or will I need a utility knife and tape measure cluttering my project space?
Installation requires only a pair of scissors or a utility knife to cut the foam to length — no caulk gun, no drill, no fasteners, and no additional materials, keeping your project space clean.
How does rubber foam compare to a door snake or fabric draft stopper for a minimalist look?
Fabric draft stoppers and door snakes add visual clutter and need to be repositioned, while rubber foam is concealed within the door or window seal, providing a permanent invisible solution.
Rubber foam vs. metal weatherstripping — which is less visible on modern windows?
Rubber foam is far less visible than metal weatherstripping, which often shows a metallic edge; foam compresses into the gap and remains hidden when the window is closed.
Does the adhesive stay flat and clean, or does it bubble and look messy over time?
The pressure-sensitive adhesive lays flat when properly applied to a clean surface, and the closed-cell foam maintains its shape without bubbling or warping, preserving a tidy appearance.
Will the foam yellow or discolor my white trim over time?
No, the black foam is color-stable, and because it is concealed in the compression gap, it does not affect the visible appearance of your white or neutral trim.
Is this a sustainable choice for an eco-conscious minimalist home?
Made in USA with a limited lifetime warranty, the long-lasting rubber foam reduces the need for frequent replacements, supporting a less-waste, buy-it-once approach to home goods.
Will the foam compress and look worn after months of use?
The closed-cell rubber foam is engineered to rebound after compression, so it maintains its profile and sealing performance rather than matting down like felt or fabric alternatives.
Is the packaging itself minimalist, or will I have a lot of waste to deal with?
The product ships as a compact roll with a release liner, producing minimal packaging waste that fits a low-waste, intentional lifestyle.
Will the rubber foam have an off-putting smell in my small, well-ventilated apartment?
Closed-cell rubber foam is low-odor and does not off-gas significantly, making it suitable for small spaces where air quality and scent neutrality matter.
How do I install the Frost King R338H self-stick foam weatherseal?
Clean the surface where the foam will be applied, making sure it is dry and free of dust or grease. Cut the foam to the desired length with scissors, peel off the release liner, and press the adhesive side firmly into place along the gap. Hold for a few seconds to ensure a strong bond.
Can I cut the foam to size without fraying or losing the seal?
Yes, the closed-cell rubber foam cuts cleanly with scissors or a sharp utility knife, and the adhesive backing remains intact along the cut edge, so you can create custom lengths for any window, door, or compartment.
How long does the adhesive take to fully bond?
The pressure-sensitive adhesive grips immediately on contact, with full bond strength typically developing within 24 hours as it cures against the surface.
Will this foam stick to painted wood, metal, vinyl, and plastic surfaces?
Yes, the adhesive is engineered to bond to a wide range of surfaces including painted wood, aluminum, vinyl, plastic, fiberglass, and glass, making it suitable for home, automotive, and marine applications.
Is this product compatible with my 2005-2007 Mustang door seals?
Yes, customers specifically use this foam to replace compromised weatherstrip on 2005-2007 Mustangs to fix water leaking onto the floorboard, and it also works on many other vehicle door panels, trunk lids, and window frames.
What comes in the box when I order this product?
You receive one 10-foot roll of self-stick rubber foam weatherseal in a 3/8" width and 3/16" thickness, in black, with a release liner protecting the adhesive backing — no additional tools or accessories are required for installation.
Is rubber foam weatherstripping safe to use in homes with allergies or asthma?
Yes, the closed-cell rubber foam does not shed fibers like felt, does not absorb moisture that can harbor mold, and helps seal out dust, pollen, and outdoor allergens, making it a good choice for allergy and asthma sufferers.
Will the foam degrade or lose its seal if exposed to direct sunlight for years?
The closed-cell rubber foam is engineered with UV resistance to maintain its structure and sealing performance under prolonged sun exposure, making it suitable for both indoor and outdoor applications.
What is the difference between rubber foam weatherseal and silicone weatherstripping?
Rubber foam compresses easily to fill variable gaps, absorbs vibration, and is more affordable, while silicone weatherstripping offers higher temperature tolerance and longer UV life but costs more and is less forgiving on uneven surfaces.
