6Pcs Hex Shank 90 Degree 5 Flute HSS Countersink Drill Bit Set

1/4 Inch , 5/16 Inch,  3/8 Inch, 1/2 Inch, 5/8 Inch, 3/4 Inch

5 Flute    (3 Flute, Single Flute, 0 Flute,  6 Flute, 7 Flute,  Multi Flute  are Available)

1.All have a 90° angle on the point for sharp and precise countersinking. The cutting edge is hardened and honed for sharpness. 
2.1/4″ hex shank countersinks are fine for a quick drill. They don’t slip in drill chucks. You can make deep countersinks easily by setting the countersink’s depth stop to allow the countersink to drill more deeply into the worksurface.