Whoever invents a technical product and then works on improving it for more than 90 years finally will reach the best possible technical standard of today. The truth itself. An Albrecht drill chuck will adhere to this truth. Self-tightening features based on practical experiences. Built with the best steel and with all essential parts hardened. This results in a drill chuck all other manufacturers worldwide have to live up to. Diamond coated jaws for clamping as per your request, 6 sizes in different range, for clockwise operation, ISO 239 or UNF.