Milton S1257 Cylinder Leakage Tester. This tester specifically pinpoints problems for a more accurate engine diagnosis. It takes over where the compression gauge leaves off. It's easy-to-use and works from a standard shop air line. Use this tool to quickly spot bad valves, worn rings, cracked cylinder walls and blown gaskets. Its compatible with standard leakage testers. This is the method professional mechanics have used for years to more accurately pinpoint the causes of low compression.