Aluminum Oxide is a general purpose mineral that works well is most applications. Ceramic minerals are very hard and provide a long lasting wheel life in high production applications. Ceramic A/O Blend is a great combination of performance and price. Cubitron II is 3M's precision shaped grain; it offers top of the line cut rate and abrasive life. Silicon Carbide is an extremely sharp, but brittle mineral. This combination provides a high cut rate and leaves a very fine finish. It is a great choice for glass, fiberglass, and ceramics.