Hardcast manufactures water and solvent based liquid applied mastic/sealants for sealing metal, flexible and rigid fiberglass ductwork. The mastic/sealants are either fiber reinforced or non-reinforced and are available in white or gray. These products are listed by UL (Underwriters Laboratory) having UL-181 A-M and/or UL-181 B-M. Available container sizes range from 11 oz. caulking tubes to 1 and 5 gallons pails.