I've been watching a show called "American Choppers" on the Discovery channel. On many occasions I watched them cut some fairly intricate curves using a 4.5" grinder with what I'm guessing isn't a regular grinding disk. Does anyone know what type of disk that is. I'm guessing it is a thinner disk. I realize skill plays a big part here but I can't believe he's making some of those cuts with a thick traditional grinding disk.