1/2" to 1/4" Router Bit Collet Extension and Reducer. Extends The Router Bit an Additional 2-1/4" and Accepts 1/4" Shank Router Bits Into the Collet Give your router bits an additional 2-1/4" when you extend them through the router table top with our router collet extension. Eliminate the dangerous temptation of withdrawing the shank from the collet in order to raise the bit and to provide the full depth of cut. This allows you to use your router when you need to make deeper cuts. This generally happens when using bits like dish carving bits and some engraving bits. The router collet extension makes it possible to use all diameters of 1/4" shank bits safely. Place the router collet extension shank in the 1/2" router collet and the router bit shank in the extension collet and tighten both Instructions included. Use with 1/2" collet routers only. Can not be used on a router with only a 1/4" collet. Your router must have a 1/2" collet to accept this extension properly