I have been using cutters for over 35 years. These bits are by far the worst bits I've ever used to make Corian. I had a small project where I used them and I will never use them on Corian again. I just threw away $400. I would give 2 stars for the sharpness of the blade. The tools used to make shells were designed in such a way that they left a small protrusion that had to be ground down. The rounded edge above the bit had a nylon bearing cap. It came off within 3 inches of starting. I had to re-cut the edge and use another of my round overlays. Never again from this manufacturer!