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Your cart is empty.Red Devil D-Seal is a smooth gray water based duct sealant/mastic used in low, medium, and high pressure duct systems; which is non-flammable and provides permanent flexibility, excellent water-resistance and superior sealing strength. Use it to seal metal to metal or flexible to metal joints to prevent air leakage. Use in conjunction with metal fasteners. Made in USA. FEATURES: LEED EQ 4.1 Compliant Indoor/Outdoor Excellent Adhesion Excellent Flexibility Low VOC USE ON: Metal and Flexible Ducts Vents Air Conditioners HVAC Appliances SPECIFICATIONS: UL 181 B-M certified ABOUT RED DEVIL: Red Devil is still a privately-owned family business with state-of-the-art manufacturing facilities in Pryor, Oklahoma. Click on the Red Devil link at the top of this page to visit our Brand Store.
Jamie Colbert
Reviewed in the United States on March 11, 2025
great buy great buy great buy
L. Olson
Reviewed in the United States on September 26, 2024
Bought this for 2 hour advertised dry time. Note dry even after 24 hours.Arrived with box crushed, no packing, and half of the gallon of mastic leaked out the Cid and into the box. Since I needed the product, I cleaned it up and salvaged the remainder.. Bad experience. Recommend just buy mastic from big box or hvac supply store.
Customer
Reviewed in the United States on November 20, 2024
After a week or so cracks all over
Jeffrey C.
Reviewed in the United States on March 1, 2023
The mastic was poorly packaged, it was shipped UPS and the top came off the container during shipping. If you used mastic before you know the mess it can make. The product works as described.
Jeff riley
Reviewed in the United States on January 6, 2023
Good value, good product
Fermin Castillo
Reviewed in the United States on December 15, 2022
I love it, used in the house
Jeff Neumann
Reviewed in the United States on May 15, 2021
I don't like the fact that this stuff doesn't stick to things very well. I got some other mastic that stuck extremely well but it was also fiberglass impregnated. I picked up recently the same version of this stuff but with the fiberglass and I'm going to give it a shot. This just feels like it peels off very easy even when it is dry. And as far as smoothness goes yeah the material or the the makeup of it is smooth but it does not go on smooth so I would not expect you to be able to smooth it out with like a body putty knife or anything like that if you were planning on sanding your ducts and painting them. Good luck. Mastic tape, much better thing for that.
Hugh T.
Reviewed in Canada on July 26, 2020
I sealed my ducts in the basement and now my basement is not that cold anymore in the summer when my A/C is running. Now I know how much money I had wasted for the last 10 years :-). Now my upstair has more air flow and cooler.
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