Guide bushes guide the router when using a template. |Fits directly to Trend routers, and some other light duty routers. |Will fit other makes when used with GB/5, GB/PLATE or UNIBASE Sub-base.|Diameters 7/8 inch (22.2 mm) to 1-5/16 inch (33.3 mm) in 1/16 inch (1.6 mm) increments.