4 - 22mm Hex Titanium Step Cone Drill Bit Hole Cutter HSS 4241 for Deburring Chamfering Main Features: ● A bit can open a variety of specifications of aperture. ● Do not need to use center punch, compared with the ordinary twist drill, it is not easy to be broken. ● Deburring, chamfering, elliptic hole enlargement. ● Use for drill, bench drill. Work with water cooling can effectively extend the service life of drill bit, recommend drilling rate is 250 - 250 RPM.