Product description boss® 334 is a one-component, minimal expanding ready to use polyurethane foam. It is fitted with a plastic adaptor head for use with a foam applicator gun. It contains cfc-free propellants, which are completely harmless to the ozone layer. low expansion. - excellent adhesion on most building materials (except teflon, pe and pp). - high thermal and acoustic insulation, very good filling capabilities. -excellent mounting capabilities and stability (no shrink or post expansion).