Aluminum oxide grain.For general purpose cutting.Combines fast cutting with long life., Aggressive cutting performance over a wide range of applications.Our unique Super-Lock??????????Hub combines both a mechanical locking system and chemical bond providing one e of the safest, vibration-free designs in the industry Super-Lock??????????Hub.All sizes reinforced with the highest quality fiberglass for maximum safety and performance.Designed to provide very long life for fewer wheel changes and less downtime.