Metacaulk® Composite Sheet is a rigid fire resistive panel, which is used to restore the fire integrity of floor/ceilings or walls in which large openings have been made to accomadate penetrants. Designed from a reinforced, highly intumescent material which is bonded on one side to a non-magnetic (#304) stainless steel sheet, helps ensure good weather ability and virtually no inductive loss in cables. In addition to sealing penetrations through large openings, Metacaulk Composite Sheet is also used for shielding cable trays, conduit, and vital process equipment from radiant heat, flame spread and smoke. The Metacaulk Composite Sheet functions as an effective intermediate fire-break within horizontal and vertical cable tray runs and is excellent for both new and retrofit construction. When exposed to a fire, the material forms a refractory char that retards heat transmission and tightly seals penetrations against flame spread, smoke and toxic fumes. It is lightweight and can be easily installed with common trade tools. It provides up to a 4 hour fire resistance. In accordance with ASTM E814 (UL1479), ASTM E119 (UL 263).