CCWI - 181 is a versatile, all purpose duct sealant for use on all types of metal duct, glass fiber duct board, and flex duct, as well as duct fabric and flexible tubing runouts. CCWI - 181 incorporates a built-in polyester reinforcement for exceptional strength, with UV inhibitors for outdoor use. -CCWI-181 is UL 181A-M & UL181B-M Listed -Passes ASTM C-731, D-2202 USDA, EPA & FDA Approved LEED compliant SCAQMD Rule 1168. -City of Los Angeles Approval RR #8427