| High quality M35 cobalt steel, 66-69 HRC (Rockwell hardness scale), generally has the best resistance to heat, wear and chipping and a long service life. > Three pass sharpening, high HRC and material heat resistance, designed to cut stainless steel, sheet iron, aluminum, pipe, wood, PVC and plastic. This cobalt step drill is typically capable of running at two to three times the speed. Despite the higher price, the cost per hole will be the lowest when using a cobalt drill bit as it produces more holes. [4-32mm] 15 grades (4mm, 6mm , 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm) When shopping, please pay attention to the size and dimensions of the product >… | |