The Snap-on Compression Gauge Set, No. EEPV500, simplifies compression testing on late model car and truck engines with hard-to-reach spark plug ports. Designed for use on spark-ignited gasoline engines, not exceeding 300 psi compression, the EEPV500 features hose-style adapters that thread into the spark plug hole and connect at the gauge hose’s quick coupler. The gauge measures 2 3/4” in diameter, displays individual cylinder pressure and includes a 27” flexible hose. Durable and easy-to-use, the EEPV500 detects piston ring, intake/exhaust valve, head gasket and other engine issues while maintaining the highest compression reading. The gauge quickly resets to zero with a push-button release valve.