Item Type: Extension Rod Product Material: 40Cr + Carbon Steel Hardness: 45-46HRC Head Diameter: Approx. 18mm / 0.7in Clamping Range: Approx. 1-7mm / 0.04-0.28in Adapter Collet: ER11 Thread Type: A Tool Shank Diameter: Approx. 10mm / 0.4in Package List 1 x Tool Holder 1 x Wrench 1. Incorrect assembly may damage the accuracy of the nut and spring2. Only the matching collet chuck can be used to assemble the nut3. Do not clamp tools that exceed the clamping range 140CR MATERIAL: Made of excellent 40Cr material, with high strength and concentricity, effectively suppressing vibration. 2INTEGRATED MOLDING: The inside and outside of the tool holder is integrally formed, with fine processing, the performance is stable. 3FOR MACHINE TOOL: After inner hole grinding treatment, suitable for high accuracy machine tool processing, with strong practicability. 4QUENCHING PROCESS: Using carburizing and quenching process, with high hardness and interface fatigue resistance. 5STANDARD SIZES: With standard shank diameter and thread, is suitable for ER11 collet, and the clamping range is 17mm.