This compression tester measures cylinder compression to accurately diagnose engine leaks from rings, burnt valves and blown head gasket. This tester has a quick disconnect coupler that separates the hose from the gauge for faster, easier connections to the engine. Also included are a push-button side release valve that allows repeated testing without disconnecting. It is compatible with all standard spark plug threads. It includes a comprehensive user manual with illustrated step-by-step automotive test procedures and has 1 year warranty.