XtremepowerUS 13" Flex Hose Compression Pressure Gauge Tester w/ Cone Adapter Checks cylinder compression from 0 to 300 PSI. (0 to 21kg/cm2) Fits 14mm and 18mm spark plug threads Equipped with air-hold valve and gauge reset button 13-inch flexible hose with 14mm and 18mm adapters Easy Reading 2-3/4" Diameter Gauge