Feature:1. After heat treatment and cold drawing hardening, the strength is relatively high, with a certain degree of flexibility.2. Quenching processing, fine workmanship, sturdiness and durability, inner hole grinding.3. Manufactured with strong clamping power, high rigidity, low noise, very good choice for you.4. Widely used for milling, drilling, tapping, engraving, CNC, half cone angle of spindle machine collet.5. High performance and high quality, the carburizing depth is above 0.8mm/0.31in, practical in use.Specification:Item Type: Back Pull ColletMaterial: 65 MnAccuracy: 0.005Hardness:> HRC48-55°Carburizing Depth: >0.8mm/0.31inSurface Roughness: >0.8mm/0.31inDiameter: Approx. 8mm/0.31inUse: Widely used for milling, drilling, tapping, engraving, CNC, half cone angle of spindle machine collet, with great clamping force Package List:1 xBack Pull Collet