GZYF Multi-Function Compression Gauge Test Set for Engine Cylinders Diagnostic Tester Gauge Set 0-300psi Fittings: M10, M12, M14, M18 (Male, With "O" Ring) Adapters for a wide number of vehicles (spark plug types/depths)Kit includes 2 rubber cones ends for quick check (no need to thread into head) 3" Gauge has dual color scale with 0-300 PSI, 0-20 kPa Spark plug thread adapter sizes: M10 x 1.0, M12 x 1.25, M14 x 1.25, M18 x 1.5 Good quality and easy to use