3-flute countersinks are designed for general purpose work.

The 3/4" and 1" countersinks have 1/2" shank. The 1/2" countersink has a 3/8" shank and the 1/4" & 3/8" countersinks have a 1/4" shank.

These countersinks are suitable for enlarging and beveling holes, typically for countersinking screw heads. They may also be useful in chamfering edges and corners of holes, and deburring sharp edges or burrs.