The NORTON SG Blaze R980P locking disc is ideal for grinding and finishing on contours or flat surfaces. Improved ceramic aluminum oxide grain provides cool cut with fast cut rate. Durable polyester Y-weight backing. Treated with grinding aid for better part finish and integrity. Speed-Lok® fastener system provides fast, tool-free disc changes. Disc locks securely to back-up pads by twisting. TR disc has rubber-threaded hub.