Feature: 1. 40CR MATERIAL: Made of 40Cr material, effectively suppressing vibration, possess high concentricity, and stable processing 2. HIGH CONCENTRICITY: The inside and outside of the tool holder are integrally formed. Fine control processing bring more stable performance and high concentricity 3. FOR HIGH ACCURACY MACHINE TOOL PROCESSING: After inner hole ground treatment, suitable for high accuracy machine tool processing and has a longer life than ordinary tool holders 4. STRONGER FATIGUE RESISTANCE: Using carburizing and quenching process, the hardness is higher, the fatigue resistance of the interface is stronger and more durable 5. 1‑7MM CLAMPING RANGE: The clamping range is from 1‑7mm, come with stable structure, excellent performance and long service life Specification: Item Type: Collet Chuck Holder Product Material: 40Cr + carbon steel Hardness: 45-46HRC Head Diameter: Approx. 16mm / 0.63in Clamping Range: Approx. 1 ~ 7mm / 0.04 ~ 0.28in Adapter Collet: ER11 Thread Type: M Tool Handle Diameter: Approx. 10mm / 0.39in. Package List: 1 x Collet Chuck Holder 1 x Wrench Note: 1. Incorrect assembly may damage the accuracy of the nut and spring.2. Only the matching collet chuck can be used to assemble the nut.3. Do not clamp tools that exceed the clamping range.