Versatile kit provides a quick means of testing cylinder compression pressure on engines with deep, recessed spark plugs and difficult access Special air hold valve is included for easy resetting of the gauge Digital pressure gauge displays readouts in PSI, BAR and KPA Set contains long flexible hose and adaptors, eliminates the need to remove secondary equipment such as A/C, power brake, manifold and steering components Measurement range digital gauge: 0-300PSI Measurement range quick check standard gauge: 0-200PSI