Duct Seal I is a fiber-free, solvent based, synthetic rubber duct sealant. It's exceptional strength, fast drying time, and unmatched flexibility make it ideal for those applications requiring a solvent based sealant. Duct Seal I's low viscosity, no-drip, no-string formulation allows fast application for labor savings and extended coverage for lower installed cost. Passes ASTM D-2202, LEED Compliant SCAQMD Rule 1168.