This compression tester is a diagnostic tool which can help you identify damaged pistons, worn rings, burnt valves, and blown head gaskets. It works on conventional, electronic, and computerized domestic and import vehicles. It features a large 2 1/2-in dial face with accurate Bourdon tube meter movement and dual-calibrated and color-coded scales. It has a 15-in high-pressure rubber hose which is oil and grease resistant, a side-release valve which allows repeated tests without disconnecting the hose, and 14mm and 18mm adaptors that fit most vehicles. Also provided are 10mm and 12mm adaptors which can be used for most motorcycles, ATV"s, snowmobiles and marine applications.