Metacaulk products are a family of firestopping products specifically designed to fill voids in construction joints and around penetrations in fire rated walls or floors. Each time a fire rated wall or floor is penetrated, it must be restored to its original fire rating. Many Metacaulk? products have intumescent properties which cause them to expand when heated, forming a high strength insulating char. In the event of fire, Metacaulk sealants will restrict the spread of flames, smoke, hot gases and water through penetration openings and construction joints. Metacaulk? sealants are tested in accordance with one or more of the following standards -- ASTM E814, UL 1479, CAN4-S115M and UL 2079 Fire Test Standards for up to a 4 hour fire rating in addition to ASTM E84, UL 723 Surface Burning Characteristics. Complies to Required Environmental Exposure Testing of Accelerated Aging and High Humidity as per UL 1479 Fire Test of Through-Penetration Firestops.