Plain Plug Gauge for Distal hole ID of the nail. Go 5.1 to 5.103 Cy. 0.001; Len. 20 to 21 or Std. NOGO 5.148 to 5.150 Cyl. 0.001 Len. 10 to 11 or Std. Gauging are should have lapped finish. Gauge No. PPG 5100.5150 