Professional cobalt drill bit for metal HSS-Co fi 10,5 mm. The collective package is 10 pcs. CNC PROFI HSS-Co drills are top quality drills that are made of HSS-Co high speed steel with 5% cobalt content. They also contain chromium and molybdenum, which increases the drill bit's resistance to abrasion and high temperatures. The drill has a hardness of 64 HRC and retains it at high temperatures. Professional cobalt drills are recommended for hard acid-resistant steel and hard-to-cut steels. Designed for: machinable steels, cast iron, alloy steels, aluminum, stainless steel.