Material: HSS（High Speed Steel）4241, Titanium Coated Application: Ideal for cutting metal, wood, plastic and thin iron plate (hardness < 25 degrees) Chamfer Range: 2-5mm, 5-10mm, 10-15mm, 15-20mm, Shank Diameter: 6mm, 8mm, 10mm, 12mm, Head Diameter: 10mm, 14mm, 21mm, 28mm 90 degree angle on the tip for neat and accurate countersinking, used for circular opening chamfering or tapered hole. These bits need to use the bench drill, it is easy to shake and it will affect the chamfering effect if you use the hand drill