Item Type: Router Collet Extension Product Material: 40Cr + Carbon Steel Product Model: C8-ER11M-100L Shank Length: Approx. 100mm / 3.94in Hardness: 45-46HRC Head Diameter: Approx. 16mm / 0.63in Clamping Range: Approx. 1 ~ 7mm / 0.04 ~ 0.28in Adapter Collet: ER11 Thread Type: M Shank Diameter: Approx. 8mm / 0.31in Package List 1 x Router Collet Extension 1 x Wrench 1. Incorrect assembly may damage the accuracy of the nut and spring; 2. Only the matching spring collet can be used to assemble the nut; 3. Do not clamp tools that exceed the clamping range. 1Stable Holding: This router collet extension rod can effectively suppress vibration and ensure stable processing. 2Accurate Using: Having been through inner hole grinding treatment, suits perfectly for high accuracy machining. 3Exquisite Work: The inside and outside of the tool holder are integrally formed, and also has high concentricity. 4Great Material: Mainly made of premium 40Cr and carbon steel materials, has high hardness and fatigue resistance. 5Easy to Install: A wrench is included in the set as well, which makes the installation more convenient to finish.