Forms a tight barrier against fire, smoke and toxic fumes. Suitable for a wide variety of through-penetration fire stops, including cable, metal pipe, insulated pipe, glass pipe, construction gaps, HVAC ductwork and certain plastic pipe applications. Cures to form a flexible seal, installs with a standard caulking gun, pneumatic pumping equipment or putty knife. ASTM, FM and U.L. tested for 3 hour fire penetration seal for walls and floors.