Application To check leakage amount in 4-stroke engines To detect engine faults like cylinder head cracks, worn valves or piston rings Display percentage of cylinder leakage pressure Specification Gauge Scale: 0-100PSI in 5% increments Spark Plug Adapters:10mm, 12mm Metric Adapter:M12x 1.25, M14x 1.5 2-1/2" input pressure gauge Package Include: Engine Cylinder Leak Tester Kit compatible for Case Color: random shipped Note No Instruction Included. Please feel free to contact us for whatever we can help.