Product Description This handy push-in compression tester has the same scale range as the CP7827. Universal rubber adapter fits all spark plug holes. Allows you to measure pressure within the combustion chamber as the piston comes up on the compression stroke. - 0 - 300 PSI (0 - 2100 Kilopascal scale) - Pressure release plunger in stem - Made in U.S.A. - User Manual (29K PDF format)