Sait Concrete C24N are United Abrasives grinding wheels providing quick action on all masonry, concrete and stone. They are made of Silicon Carbide, have a course grain size and a soft bond for fast stock removal. Applications: Masonry, concrete, stone; cast iron and other non-ferrous metals. 4 1/2" diameter, 1/4" thick, Type 27 (depressed center), 7/8" bore, no hub. For right angle grinders.