3M™ Fire Barrier Moldable Putty Pads MPP+ are a one-part firestop material used in various fire-rated assemblies, such as electrical box protection. Designed to prevent the spread of fire, smoke and noxious gasses, this intumescent material comes ready to use in convenient 1/10" (2.54 mm) thick pads that are conformable by hand with no mixing or tools. Pads are firestop tested up to 2 hours.