perfect for making countersunk countersunk holes and countersunk holes for plugs. The countersinks are carbon steel, the is titanium coated, sturdy and , not easy to rust, long service life. This kit is suitable for DIY and daily use, it allows to drill easily and effectively, without burr. Universal size compatible with all types of drill, drilling machines, including vertical drilling machine, and another common milling cutter. Used in hardness 25 under the part, such as carbon steel, sheet metal, insulation boards, PVC board, wood For the 90 ° chamfer piece hole or conical hole, the chamfer edge edges and angles of the treatment angle Can be completed finished the treatment of the cone for one time. Applicable to the small cutting process. Neat edges, smooth, no broken edge, small resistance to chamfering, high precision in the hole, more Flute with big chip, fast for the elimination of chips Three blades of medium for laborious, each force of the blade smaller, high efficiency and