Soudafoam Gun Gap Filler Xtra is a one-component, self-expanding, ready to use polyurethane foam, which contains HCFC- and CFC- free propellants which are not harmful for the ozone layer and where the canister is provided with a thread so it can be used on a gun. Because of the Duravalve, the optimal yield remains over the entire shelf life, even when stored or transported lying down.