These two-flute, countersink/counterbore 1/4″ hex-shank bits have standard twist drills. A set screw holds the drill at any projection. Counterbore size is 3/8″, except for the #10, which is 1/2″. This four piece set includes: #6, #8, #10, #12 High Speed Steel Hex Shank Drill Bits with Counterbores
– High speed steel (HSS)