6-piece UltimateCut Countersink Set 4S DIN 335 90° Ø 6.3 - 8.3 - 10.4 - 12.4 - 16.5 - 20.5 mm. Can do better. Can do faster. Can do longer. The UltimateCut Countersink 4S in HSSE-Co5 offers a longer service life for quicker work results. The newly developed UltimateCut Countersink 4S 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 the new UltimateCut Countersink 4S 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. Another advantage: For the first time, the newly developed cutting edge technology enables countersinking with diameters of up to 40 mm using handheld screw and drilling tools. The new UltimateCut Countersink 4S works equally precisely in pillar drilling machines as well as in CNC-controlled machining centers. The new UltimateCut Countersink 4S comes standard with a 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 by RUKO, guarantees even higher performance. Particularly with demanding materials, such as alloy steel, the coated RUnaTEC variant impresses with powerful penetration into the material and significantly improved wear resistance.