Please visit the Guide Bushing Adaptor Selector to confirm the correct adaptor for your router.
The Leigh dovetail jigs use a guide bush system to guide the router bit around the fingers of the template. A guide bush is held in a rebated 30mm hole, making all of the bushing flush with the rest of the router base other than the guide itself.
The adaptor fits into the base of the router, and usually is held in place using screws. As the bases of routers are not standardised, Leigh have a range of adaptors to suit most common routers. These adaptors are not suited to all routers, but a range of larger 1/2” shanked routers.
Guide bushes are not limited only to Leigh jigs, but can be used as an alternative to pattern router bits. The router bit needs to be smaller in diameter than the inside diameter of the guide bush, and rotate freely. The jig it is being used with needs to made to accommodate this difference, the OD (outside diameter) of the template to the OD of the bit.