Our best choice for maximum stock removal.Premium high ratio ceramic grain for increased efficiency and performance.Type 27., Highest quality ceramic aluminum oxide grain assures consistent high stock removal for tough applications.All sizes are made with uniform grain throughout, no filler grain used.All wheels are internally reinforced with the highest quality fiberglass for maximum safety.Our unique Super-Lock?âòÀÞ?â Hub combines both a mechanical locking system and chemical bond providing one of the safest, vibration-free designs in the industry.