Aluminum oxide grain Medium bond for longer life and fewer wheel changes Type 28 saucer shape for uniform grinding of large flat surfaces and greater grind visibility Additional fiberglass reinforcement for maximum safety Unique Super-Lock Hub combines both a mechanical locking system and chemical bond providing one of the safest, vibration-free designs in the industry The A24R is a Type 28 grinding wheel that provides consistent performance with long life for fewer wheel changes. The saucer shape of the Type 28 wheel allows for uniform grinding of large flat surfaces, and provides the operator with greater grind visibility. Wheels are reinforced with the highest quality fiberglass for maximum safety. Unique Super-Lock Hub combines a mechanical locking system with a chemical bond to provide one of the safest, vibration-free designs in the industry. Used for ferrous metals such as iron, steel, welds, etc. Package of 10.