6-piece UltimateCut Countersink Set DIN 335 90° Ø 6.3 - 8.3 - 10.4 - 12.4 - 16.5 - 20.5 mm. High working quality, lower costs. The newly developed UltimateCut Countersink 4S operates with four cutting edges instead of three. The distribution of the forces acting on the four edges significantly reduces axial and radial forces and ensures an extremely smooth and material-friendly operation of the tool due to the unequal distribution. This means that the new UltimateCut Countersink 4S not only provides a perfect countersink profile without chatter marks but also allows for particularly energy-efficient and material-friendly work, achieving up to 50% time savings and up to three times longer tool life. Another advantage: For the first time, the newly developed cutting edge technology allows for countersinks with diameters of up to 40 mm to be performed with handheld screw and drilling tools. The new UltimateCut Countersink 4S works equally precisely in pillar drilling machines and CNC-controlled machining centers. The new UltimateCut Countersink 4S features a standard 3-flat shank that prevents slipping in the drill chuck and ensures consistently optimal power transmission during the working process. RUnaTEC: Even more wear-resistant, even more aggressive in material removal. The RUnaTEC coating, developed in-house by RUKO, guarantees even higher performance. Especially with demanding materials, such as case-hardened steel, the coated RUnaTEC variant impresses with powerful penetration into the material and significantly improved wear resistance.