For hand application and locations where periodic cable changes are anticipated, moldable putties are used to fill penetration openings. Like caulks, such materials form a cold smoke and gas seal, and have both intumescent and endothermic properties. Whether you need preformed plugs or the flexibility. Firebreak 55 Fire Resistant Non-Setting Putty is made from silicone based ablative polymer with additional fire resistant additives, and is designed to reinstate the fire resistance of small cable service penetrations through walls. Putty is formed or molded to fit a cable opening. A flexible intumescent putty, ideal for use around copper pipes or cables, and around steel electrical trunking.