5pcs/2pc 60 Degree HSS Center Spotting Drill Bits Combined Countersink High Speed Tool Material: HSS;60 degree tip angles Optional Size: 1/8",3/16",1/4",5/16",5/32" Applicable hardness: HRC40 or less Suitable for positioning and Chamfering processing before drilling Cutting fast, good chip evacuation, edge clear, sharp and durable