Compatible with direct and indirect petrol engines that use 10, 12, 14 and 18mm spark plug threads. Accurately detects common engine faults such as worn piston rings, worn valves, cracked cylinder heads and blown head gaskets. Twin gauges indicate both cylinder pressure 0 - 100psi/0 - 7bar and percentage of cylinder leakage. Both gauges are fitted with heavy duty rubber protectors. Supplied in a plastic storage case.