This is a large block of steel. The image shown has a much smaller bit. The 50-138 measures 2" x 2" and is few and far between. The hard metal is fine-grained and razor-sharp. Really works without vibration. I've used it by hand to trim some of the doors in my house. He cut through her like a knife through butter. The instructions only recommend using the router chart, but I had no problems with the Bosch variable speed router. This takes a few extra seconds due to centrifugal force.