Tough and ready-to-use, 3M™ Fire Barrier Sealant CP 25WB+ is a high-performance, one-component, latex-based, intumescent sealant that dries to form a monolithic firestop seal. This sealant also acts as a barrier to airborne sound transmission. As penetrants are exposed to fire, the unique intumescent property of this material allows 3M™ Fire Barrier Sealant CP 25WB+ to expand and help maintain a firestop penetration seal for up to 4 hours. This sealant is designed to help control the spread of fire, smoke and noxious gases before, during and after exposure to a fire when installed in accordance with a listed through-penetration or fire-resistive joint assembly system (STC-Rating of 54 when tested in a STC 54-rated wall assembly).