1)Best material:42CrMo &YK05 2)Tapered:6,7,11,12 3)Technology:cold pressing Features:1) Tapered connection: 6°, 7°, 12o2) Threaded connection: R22, R25, R28, R32, R38, T38, T45, T513) Diameter: 30-127mm4) Available types:a) "Retrac" button bitsb) Drop center button bitsc) Flat button bitsd) "Retrac" drop center button bitse) Reaming bits Packaging: wood or plastic box package