This P120 grit quick-change sanding disc can be run wet or dry. It has aluminum oxide abrasive with durable YF-weight polyester backing that is water-resistant and resin-bonded for heat resistance. Ideal for use in welding, metalworking, maintenance, repairs, and operations, this roll-on sanding disc and can withstand grinding speeds up to 30,000 RPM. This sanding disc is 1 1/2 inches in diameter.