A two-component RTV silicone foam that features excellent crack-and-void filling capabilities. Marine Firestop Foam exhibits uniform cell structure, assuring reproducible, smoke-tight, fire resistant installations. The elastic properties of the foam readily accommodate minor vibration of the pipe, conduit, etc. without loss of system integrity. Used in a 1:1 mix ratio, Marine Firestop Foam, when properly mixed, expands 2 to 4 times its original volume, filling available spaces and forming an effective barrier against fire, smoke and water penetration.