Cleans any size spark plug quickly and effortlessly with internally controlled abrasive blasting. Uses ordinary air line pressure. Compressed air flows through special venturi mixing with abrasive to thoroughly clean spark plugs like new. Lever valve on outside of unit allows for blasting with abrasive/air mix or pure air only. Abrasive material is included and is silica free. Recommended air line pressure is 70ñ80 PSI; maximum 90 PSI. Instructions provided.