Arc Expanding Foam is a one-component, self-expanding, ready to use Polyurethane foam with CFC-free propellants, which are completely harmless to the ozone layer. It is available in 2 types, one that can be used with the supplied straw and one that can be used with a foam application gun. The foam will expand and cure by moisture in the air. It is used for a wide range of building applications. It is great for filling and sealing with excellent mounting capacities, high thermal and acoustical insulation properties.