Grizzly H2947 - 4 pc. HSS Socket Cap Screw Counterbores

This is the ultimate in a 3 flute high speed steel counter bore set. The pilots are precision ground to clearance hole dimensions which are clearly marked on the shanks. The shanks are ground to fractional inch dimensions so they can be secured in collets as well as drill chucks. Counter bores are sized for the heads of #10, 1/4", 5/16" and 3/8" cap screws.