DURASIL FR Firestop Sealant is a flexible medium modulus acrylic-based joint and penetration sealant for indoor and covered outdoor use. With incorporated high solid Firestop compound, it effectively seals joints and seams in compartment walls & floors against the spread of fire, smoke, toxic gases and water up to 4 hours. It adheres to most construction materials and is applicable for areas where fire resistance is mandatory.