1、More Stable Clamping: After high frequency quenching treatment, good low temperature impact toughness and good clamping performance, the clamping is more stable 2、High Wear Resistance: The surface is grinding and polished, high wear resistance and heat resistance, and the bright outer surface fits better to ensure excellent accuracy 3、Good Stability: Chuck has large elasticity, strong clamping force, good stability, no vibration, and no loosening 4、Application: Suitable for ER tool holders, shanks, extension rod nuts, clamping bits, boring cutters, engraving knives, reamer tools 5、Spring Steel: Made of high quality spring steel, high temperature resistance, corrosion resistance and stable performance7 x Spring ColletItem Type: Spring Collet SetMaterial: Spring SteelClamping Range: Approx. 1mm-7mm / 0.04-0.28inTolerance: Approx. ±0.01mm / 0.0003inQuantity: 7PcsScope of Application: Suitable for ER tool holders, tool holders, extension rod nuts, clamping drills, boring tools, carving tools, reamers