FROTH-PAK™ 650 Low GWP Insulation Class A Fire Rated, Applicator, Hose & Nozzles. Low GWP Spray Foam Insulation Kit, FROTH-PAK™ 650, Class A Fire Rated. FROTH-PAK™ 650 Class A fire rated spray foam insulation kits are complete portable two part polyurethane spray foam systems.