3M Cubitron 3 1182C fibre disc uses precision shaped ceramic aluminum oxide as the abrasive material and has a diameter of 4 in. 3M incorporates this precision shaped ceramic aluminum oxide material into the fibre disc forming a grit of 36+. All abrasive products that rotate or spin, such as the ones in this category, have a maximum speed at which you can run them. This 3M fibre disc can be run at a maximum speed of 15000 RPMs.