Roloc discs for use in general metalworking and heavy duty woodworking. Type-R discs with a roll-on/roll-off style fastener for quick change and to prevent fly off at high speeds. Premium aluminum oxide resin bond for excellent durability. Recommended for use with difficult to grind materials. Works great on aluminum, stainless, mild to medium steel, and some alloy metals. Several grits for different applications. 50 Discs.