... precision:0.005mm hardness:HRC 44-46 used for boring, milling, drilling ER miling Collets chuck sets ER collets DIN6499 full ... Collets are applied for a variety of processing, including drilling, milling tapping &grinding.ER spring collet 1.material:65 Mn 2 ... :HRC 44-46 4.used for boring, milling, drilling, etc...Model Number: ERER Milling Collet Collet CNC lathe chuck ER,OZ, Sealing ...