Taper and deburring countersinkers type C 90° HSS. The flutes of the new RUKO high-performance taper and deburring countersinkers are CBN ground from the fully hardened material Because CBN (cubic crystalline boron nitride) is a much harder abrasive than even silicium carbide or corundum, a better and sharper cutting edge is achieved - without burrs. And, with higher dimensional precision the countersinkers will last considerably longer while maintaining the precise tolerances. Because of the CBN deep-ground lutes the cutting edges are extremely sharp. Ideal for burr- and chatterfree deburring and countersinking. Applicable for steel, cast iron, non-ferrous and light etals. Best results at low cutting speeds.