Measures the ability of an engine cylinder to hold compressed air. Hooks up to the shop air compressor to supplement for a compression tester. Includes a precision regulator, M14 standard reach adaptor with 26 in. hose assembly and M14 long reach solid adaptor. M68 special gauge has one multicolored band for measuring low, moderate and high leakage, and a scale range from 0-100%. Second M68 gauge has a dual scale dial with ranges from 0-35 psi, which allows the Technician to monitor input air-line pressure.