Use the router bushings kit with a router to machine grooves into a work piece with various router bit profiles and various size router bushings. These bushings used WITH OR WITHOUT the Smart Ruler & Smart Ruler XL. Without the smart ruler you can simply stick a single template to a work piece and use the edge of the template as a guide to cut a groove. 
 
Includes:
7 Router Bushings & 1 Lock Nut. These bushings fit industry standard 1-3/16" router mounting holes (ALL Porter Cable routers and MANY other brands, simply measure the plate on your router, nearly every router on the market uses this hole size)
 
Use in conjunction with the Smart Ruler or Smart Ruler XL to machine perfect grooves into your build!
 
(Router shown for illustrative purposes. Not included.)