Specification: Item Type: Router Collet Extension Product Material: 40Cr + Carbon Steel Hardness: 45-46HRC Head Diameter: Approx. 19mm / 0.75in Clamping Range: Approx. 1 ~ 7mm / 0.04 ~ 0.28in Adapter Collet: ER11 Thread Type: A Tool Shank Diameter: Approx. 20mm / 0.79in Package List: 1 x Router Collet Extension 1 x Wrench Note: 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. Feature: 1. Collet Holder: Enables effectively suppressing on vibration, this collet extension rod can promote stable processing. 2. Accurate Uses: Having been through inner hole grinding treatment, ensures high accuracy and efficiency for machining. 3. Advanced Work: The inside and outside of the tool holder are integrally formed for better concentricity in working. 4. Good Material: Adopting premium 40Cr and carbon steel materials, has good hardness and great durability with fatigue. 5. Easy to Install: Comes with a wrench, the installation is very convenient and can be quickly finished within minutes.