Diagnoses engine compression problems with this easy-to-read digital gauge. 300 PSI digital gauge with a rubber boot, and a quick disconnect fitting. The 12 in. hose has a stepped adapter for 14 and 18mm plugs, plus a 10 and 12mm adapter. Gauge holds the reading for 90 seconds, or until the RESET button is pressed. Automatically shuts off after 3 min. includes a 9V alkaline battery.