This motor shaft collet is made of high quality steel material, straight shank with clamping nut to be tightened. Extension rod diameter and the other parts are precision ground to unbalance, increase safety when cutting. Straight extended shank fits for deep processing, meeting the needs of extending the depth of processing. Collet is well packed in a protective container with label for safe transportation and storage. It is widely used in boring, milling, drilling, tapping, grinding and other processing. This collet is made of high quality steel for milling lathe tool and work-holding engraving machine. ER straight rod type collet extension handle body is relatively long, suitable for deep hole processing. The nut can be directly tightened to provide a powerful clamping force. This collet can reduce costs, improve efficiency and would be a good replacement part for your old one. Type: ER11A-8mm Color: black,silver Material: 45 Steel Height: 40mm / 1.57 inch Shaft Diameter: 16mm / 0.63 inch Shaft Inner Diameter: 8mm(+/-0.02mm) / 0.31 inch Nut Diameter: 19mm / 7.48 inch Nut Inner Diameter: 9mm / 3.54 inch Package included: 4 x ER22 A-8mm Motor shaft tool holder Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.