3M IC15WB , 10.1 ounce, yellow, intumescent firestop will maintain a firestop penetration seal  for up to 3 hours. IC15WB is used typically in mechanical, electrical and plumbing applications to firestop openings created in fire rated floors, ceilings, walls, metallic and plastic pipes, communication cable, cable trays, insulated pipe and hvac duct penetrations.