3M Fire Barrier Mortar is a lightweight, gypsum-based powder that mixes with water to form a heat-absorbing firestop for through penetrations in fire-rated floor or wall assemblies. Versatile mortar can be mixed self-leveling or non-sag, and adheres to a range of construction substrates and penetrants. It also acts as a heat sink, reducing the chance of fire on unexposed sides of the assembly.