diameter: 10mm length: 100mm Extension rod diameter and the other parts are precision ground to eliminate unbalance, increase safety when cutting. It can reduce the use of extension tools, which can reduce costs and efficiency Spring is highly clamping force, wide clamping range, high accuracy Widely used in boring, milling, drilling, tapping, grinding and other processing Color: silver + black Material: Steel chuck model:C10 ER8A 100L Spring Gripping Range:2MM to 5MM (2mm,2.5mm,3mm,3.5mm,4mm,4.5mm,5mm) Spring MODEL:ER8 Package include: 1 x Straight chuck 7 x Spring Only the above package content, other products are not included. Note: Light 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.