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.