This corner Rounder may very well be the easiest one I've seen yet. Setup is simple. First you need to know what size radius you want, then you insert 4 pins into the bottom of the large bar (these 4 pins locate the bar onto the countertop) and set the bar onto the top to be cut. Then, on the top bar, you locate the hole with the same radius number as you used on the bottom bar. That hole is set onto a fixed pin located at the center of the large bar (this pin becomes your pivot point for the radius). Both the top and bottom bar are clearly marked so it's easy to setup for any radius from 1 1/2" to 9", in 1/2" increments. A 5/8 diameter bronze bushing is located in the top bar and will except a 5/8" OD template guide fitted to a router of your choice. Simply set your router onto the bushing and you're ready to cut your radius. Making a radius has never been simpler and the best thing is, is that you don't have to buy a router with it! An inside radius is made in a similar fashion.