FST duct sealant is available in two cartridge sizes. FST-250 is used for 2-inch (50mm) or larger conduits and comes in a multi-use single-plunger caulking tube that uses a standard high-ratio caulking tool (TOOL-250). FST foam wets and adheres to metals, plastics, and concrete, and can seal ducts of different sizes, base materials, and shapes. It conforms around complex cable fill configurations.