Underbody Coating Gun Air Operated. This is a top quality spray gun specifically designed to fit most types of underbody coating can. Can be used to apply both solvent or water-based underbody coatings such as 3M Body Schutz, U-pol Gravitex or similar. Can also be used for injecting cavity wax products into door shells etc. It comes complete with instruction sheet and cavity wax injection hose.