True Shine Ceramic Transitional Cup Wheels is a ceramic bonded cup wheel for grinding edges in the concrete polishing process. Ceramic will give you a finer scratch and better finish at the end of your job. This eliminates the need of using metal bonded cup wheel that leaves deep scratches or gouges the concrete. Professional Concrete Floor Polishing Ceramic Cup wheels come in 30#grit - 200#grit. 7" Ceramic cup with a threaded arbor.