SET OF 4 CUSTOM COUNTERBORES. ALL ARE 1-7/8 OAL, DIMENSIONS ARE, SHANK .375 PILOT .373 CUTTING .452, SHANK .312 PILOT .310 CUTTING .382, SHANK .25 PILOT .248 CUTTING .311, SHANK .25 PILOT .185 CUTTING .233. I REMOVED THE DIP FROM THESE AND THERE IS NO INDICATION THEY WERE EVER USED. GOOD BASIS FOR CUSTOM TOOLING OR ?????