#1 Home Improvement Retailer

Internet #303223987

Model #1943973

Store SKU #1002938767

GS121 10 fl. oz. Clear Gutter Sealant

  • Gutter seam clear sealant that cures to a rubbery gasket
  • Permanently flexible, water resistant seal
  • Seals around most common gutter, aluminum and downspout materials
  • View More Details
0 in stock
Text to Me
How to Get It

Frequently Bought Together


Product Overview

GS121 is designed for sealing around aluminum, galvanized and vinyl gutters and downspouts, sealing seam, joints and cracks in gutter troughs, and for use on sheet metal, air conditioning and heating ducts and ventilators. GS121 expands and contracts with temperature changes, cures to a tough rubbery gasket while remaining permanently flexible. Gs121 cleans up with mineral spirits.
  • Permanently flexible
  • Water resistant seal
  • Seals most common gutter and downspout materials
  • Expands and contracts with temperature changes
  • Cures to a tough rubbery gasket
  • Mineral spirits clean up
  • For use on gutters and downspouts
  • Also available in a 5oz squeeze tube
  • California residents

Additional Resources

From the Manufacturer

You will need Adobe® Acrobat® Reader to view PDF documents. Download a free copy from the Adobe Web site.



Individual size (oz.)10


Caulk FormStandard TubeCaulk TypeSolvent Based
Color/FinishClearCoverage (linear ft.)30.6
Cure Time (hours)160Dry Color FamilyClear
Dry to touch (min.)30 minFeaturesPermanently Flexible
KitNoLongevity20 years
Number of Tubes Included1Paint Tool Product TypeCaulk

Warranty / Certifications

Certifications and ListingsUL ClassifiedManufacturer WarrantyNone

Questions & Answers

Typical questions asked about products:

  • Is the product durable?
  • Is the product easy to use?
  • What are the dimensions of the product?

Customer Reviews

  • 4.3
    out of 294 reviews
  • 90%recommend this product
Filter by:
Showing 1-10 of 294 reviews
Great Sealant!
[This review was collected as part of a promotion.] i got the OSI GS121 clear Seal , because we got a new bathroom sink and i was instaling it, and then sealed betwen wall and sink. it works great, looks good and is easy to apply. i also used it to reseal outside by the gutter, and no probleme. it is water resistant. this product is great and dont make a mess. I defently recommend it!
    • Recommended
    Works great
    [This review was collected as part of a promotion.] I bought this 3 weeks ago for a bathroom project. The packaging was good. The sealent comes out very easily from the tubing. I used it for my shower door to secure and prevent leaking. It works perfectly. I would recommend this, it’s seal really good.
      • Recommended
      Gs121 clear
      [This review was collected as part of a promotion.] This works really well with my gutters i put it on this weekend and so far its working really good.
        • Recommended
        Great water proofing
        [This review was collected as part of a promotion.] I recently had to re-route a downspout that was causing concrete problems. Afterwards I needed to seal the seams to prevent excess water flow from spilling out. The OSI gs121 did the trick. It had a good viscosity that was easy to apply. It set up in a much shorter period of time than the stuff I have previously used for this. It has a nice rubbery texture and so far has done a great job. (3 heavy rains and 1 snowfall this season). I would definitely use it again.
          • Recommended
          GS121 Clear Silicone Adheshive
          [This review was collected as part of a promotion.] Great product as you can use it for all sorts of projects around the house. It is made specifically for water proofing and that just what it does. I was able to seal the metal framing for my shower to the base and it hold water from the outside just perfectly. On top of that it dries clear so it's hardly noticeable. It also dries within an hour or so, so your project completed itself rather quickly. I would definitely recommend this product to anyone in need of a clear silicone if they were looking for a quality product with great turn around time
            • Recommended
            Perfect For Gutters!
            [This review was collected as part of a promotion.] After using this gutter sealant, I am very pleased. This sealant works extremely well at bonding any sort of cracks you may have on your sheet metal. I had applied this product to a small area on my gutter that was cracked and upon doing so, noticed a very quick improvement. It is only supposed to take about a week before the product completely cures. However, the product seems to quickly develop a tough, thick seal long before it has even fully cured. Another great feature about this product is its ability to withstand the outdoor elements. It recently snowed at my residence and this product still stayed perfectly sealed onto my gutter. I also really like the size of bead that the sealant comes out in. It is not too think or too thin. The only disadvantage of this product is that it is a little sticky and difficult to remove if you make a mistake while you are applying it. However, this is not really a big problem. Overall, I’m extremely happy with the strength and features of this sealant and would highly recommend it.
              • Recommended
              Hard Time Using Product Did Not Want To Come Out I Believe Was Old Bottle That Has Been Sitting A...
              Hard Time Using Product Did Not Want To Come Out I Believe Was Old Bottle That Has Been Sitting A Long Time!
              • Verified Purchase
              Works well
              Secure seal. Worked as intended.
              Response from OSI - Henkel CorporationJun 16, 2022
              Thank you for choosing OSI for your project! OSI
              • Verified Purchase
              My almost irrelevant review
              I gave it five stars(so far) but this is mainly price and appliction. The long game is durability over time. I can't answer this question because this is the first time I have used the product. With surfaces properly cleaned and prepped you should see 10-15 years without leakage. The clock is now ticking... we'll see!
              Response from OSI - Henkel CorporationMay 26, 2022
              Thank you for choosing OSI for your project! OSI
              • Verified Purchase
              Horrible product! Stop selling it!!...
              Horrible product! Stop selling it!!
              Response from OSI - Henkel CorporationJun 22, 2022
              We’re sorry to hear our product didn’t work as you expected. Please give us a call at 1-800-624-7767 and let us know the details about your application so we can help you have a positive future experience. OSI
              • Verified Purchase
              Showing 1-10 of 294 reviews