Feature: 1. The collet is integrally formed with a long total length and is suitable for installation on a knife sharpener. 2. The clamping force is strong, and the clamping accuracy is 0.02mm, which is suitable for fine operation. 3. The accuracy of the aperture is high, the thread size is standard, and it is not easy to fall off during installation and use. 4. Different size specifications have different clamping ranges, which are suitable for different clamping situations. 5. Made of high-quality metal materials, the hardness is HRC40-45, and it is not easy to be squeezed by the outside world. Specification: Item Type: Sharpener Chuck Model: 3-9mm Grinding Machine Chuck Hardness: HRC40-45 Clamping Accuracy: 0.02mm Clamping Range: Approx. 3mm / 0.12in, 4mm / 0.16in, 5mm / 0.2in, 6mm / 0.24in, 7mm / 0.28in, 8mm / 0.31in, 9mm / 0.4inCollet Total Length: Approx. 122mm / 4.8in Collet End Diameter: Approx. 20mm / 0.8in Tail Thread: M20 Tail Thread Length: Approx. 29mm / 1.1in Rod Diameter: Approx. 20mm / 0.8in. Package List: 1 x 3mm Chuck Note: 1. Put each type of chuck into the corresponding diameter tool to avoid damage to the chuck because the diameter of the tool exceeds the size of the chuck model.2. When changing tools, clean up the impurities inside the jacket in time to ensure the service life of the chuck.