Stores maximum compression value up to 12 cylinders. Backlit LCD for easy to read from any angle and in any light. Uses standard 9V battery. Automatically shuts off after 3 minutes of non use (memory retained). Rubber boot protects the gauge from bumps and drops Sealed, grease and oil resistant gauge face prevents contamination of electronics. Displays values in PSI; Bat and kPa. This comprehensive gasoline engine compression test kit features an electronic tester that memorizes the peak compression value for each cylinder. When testing is complete, the values can be quickly reviewed at the push of a button. Everything is included to perform wet and dry compression tests commonly used to detect ring or cylinder head problems, sticking valves, blown head gasket(s) and more. Includes adapters for use on motorcycles and marine and small engines, and an air-hold adapter for performing valve seal repairs without removing the cylinder head(s). Not for use on diesel engines.