6-piece UltimateCut Countersink Set 4S DIN 335 90° Ø 6.3 - 8.3 - 10.4 - 12.4 - 16.5 - 20.5 mm. The UltimateCut 4S countersink in HSSE-Co5 offers a longer service life for faster work results. The newly developed UltimateCut 4S countersink operates with four cutting edges instead of three. The distribution of forces across the four cutting edges significantly reduces axial and radial forces, ensuring an extremely smooth and material-friendly operation of the tool due to the unequal distribution. This means that the new UltimateCut 4S countersink not only provides a perfect countersink appearance 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. For the first time, the newly developed cutting edge technology enables countersinks with a diameter of up to 40 mm to be performed with handheld screw and drilling tools. The new UltimateCut 4S countersink operates equally precisely in pillar drilling machines as well as in CNC-controlled machining centers. The new UltimateCut 4S countersink features a standard 3-flat shank that prevents slipping in the drill chuck and ensures consistently optimal power transmission during the work 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 alloy steel, the coated RUnaTEC variant impresses with powerful penetration into the material and significantly improved wear resistance.