Available Bits Alpen Cobalt Nirosta drill bit 4.00 mm. ALPEN AFT 09085880 €4.38 Alpen Cobalt Nirosta drill 4.00 mm.Diameter: 4.0 mm.Special sharpening that guarantees optimum chip evacuation.Great cutting precision and auto Optimum centering.Higher feed and drilling speed.Specially indicated for tough and hard materials, such as stainless and acid-resistant chrome-nickel steels. Add to basket