Diameter: 1/4inch (6.35mm), Accept Size: 1/4inch and 1/2inch , Extend Length: 2-1/4inch. This router collet extension chuck accepts both 1/4inch and 1/2inch router bits for converting and extending. Converter Adapter and ER20 Collet Made of durable steel for maximum strength and long life ; ER20 M Type Collet Chuck Wrench Spanner Made of High Carbon Steel, Anti-slip handle Design, for ER20 M Lathe Clamping Nut. High , stable performance. Extend your router bit to the full depth of cut, for both 1/4 inch and 1/2 inch router bits. Eliminate the dangerous temptation of withdrawing the from the collet, extend the bit to the full depth of cut. Place the router collet extension in the 1/4-inch router collet and the router bit in the extension collet and tighten both. This router collet chuck the additional depth of cut needed for many routing tasks. Easy to , better to control, it will your work efficiency. Colour: silver Material: carbon steel Package Contents: 1 * 1/4inch handle extension rod 1 * ER20 1/4inch collet 1 * ER201/2inch collet 1 * ER20M wrench Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.