Feature: 1. Stable Performance: The router bit collet uses it to achieve the full depth of cut when processing dovetail splines, suitable for a variety of woodworking applications. 2. High Quality Materials: This chuck is made of industrial grade materials, offering high accuracy, sturdiness, durability, and long service life. 3. Easy To Use: Insert the router bit collet extension handle into the router bit collet, place the milling cutter or drill bit into the extension chuck, and tighten securely. 4. Good Packaging: Each chuck is marked with its size and individually packed in a protective container with labeling for easy identification. 5. Wide Range Of Applications: Suitable for boring, milling, drilling, tapping, engraving, CNC, and spindle machine tools. Specification: Item Type: Router Bit Extension Rod Material: Carbon Steel Extension Rod Total Length: Approx. 85mm / 3.35in Extension Rod Outer Diameter: Approx. 28mm / 1.10in Nut Diameter: Approx. 28mm / 1.10in Nut Height: Approx. 20mm / 0.79in ER20 φ13 Collet: Height: Approx. 32mm / 1.26in Outer Diameter: Approx. 20mm / 0.79in Inner Diameter: Approx. 13mm / 0.51in ER20 φ6.5 Collet: Height: Approx. 32mm / 1.26in Outer Diameter: Approx. 20mm / 0.79in Inner Diameter: Approx. 6.5mm / 0.26in Application: Suitable for boring, milling, drilling, tapping, engraving, CNC, and spindle machine tools. Package List: 1 x ER20M Nut 2 x ER20 Collet 1 x 1/2in Shank Extension Rod 1 x Wrench Note: 1. Please allow 1-2mm error due to manual measurement. Thanks for your understanding. 2. Excessive working speed may cause deformation due to high force.