Plain Plug Gauge for Device ID Go 3.003 to 3.005 Cyl. 0.001 Len. 25 to 26; with tapping of M2; NOGO 3.095 to 3.1 Cyl. 0.002 Len. 10 to 11 / Std. Gauging area should have lapped finish. Gauge No. PPG 3000.3100