I have a built in bay window and needed to replace the windows but was able to keep the frame without having to make a new window sill. This also meant that I had to change chairs. The stool was custom sized so I had to cut it into larger boards and then profile it. This bit was significantly cheaper than others I could find. Well I only needed 12 linear feet. Buying this attachment, a new collet (mine got lost somewhere!) and two 8ft planks was cheaper than buying a 12ft stool that wasn't big enough. Easy to use but I have a router table and it's a big help.