The Combination Router Base is a retro fit, quick change, multi-functional router base designed to: Increase the overall versatility of the router, Improve the quality of finish of every routing pass, Reduce the possibility of error, Increase stability during routing, Increase the level of precision achieved, Save set up time between tasks, Save space on storing hand made jigs. The CRB has seven functions - an offset baseplate, router compass from 19mm to 224mm radius, adjustable trenching with a clamp guide with 40mm micro adjustment, adjustable anti-tilt support, adjustable mortising of timber from 50mm to 200mm width, adjustable false panel groove copier and also enhances the Varijig frame system as an anti-tilt device when used with routers that can accept Euro style guide bushes (a special guide bush ref GB40/B is required).