Resin bonded, paper-backed zirconia alumina discs are extremely fast cutting, thin, and flexible. Ideal for use on platinum, all other precious metals, titanium, and other non-ferrous metals. Used for pre-polishing, semi-finishing, and blending. Discs have brass center hubs for mounting on snap on disc mandrels (see related products below). Choose between 2 diameters: 3/4" and 7/8". Maximum speed 30,000 rpm. Packed 50 discs to the box. Made in USA.