Features： 1、Stable Performance: The router bit collet uses it to achieve the full depth of cut when processing dovetail splines, which is very suitable for a variety of woodworking. 2、High Quality Materials: This chuck is made of industrial grade materials, with high accuracy, sturdiness and durability, and long service life. 3、Easy To Use: Put the router bit collet extension handle into the router bit collet, put the milling cutter drill bit handle into the extension chuck, and tighten the two. 4、Good Packaging: Each chuck is marked with a size and is well packed in a separate protective container with a label, so it is easy to distinguish them. 5、Wide Range Of Applications: These kits are suitable for boring, milling, drilling, tapping, engraving, CNC, spindle machine tools and other processing. 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: These kits are suitable for boring, milling, drilling, tapping, engraving, CNC, spindle machine tools, etc. Package List： 1 x ER20M Nut 2 x ER20 Collet 1 x 1/2in Shank Extension Rod 1 x Wrench