United abrasives – sait 20088 depressed center wheel t27 a46n 7″x 1/4″x 5/8-11″ aluminum oxide features: special aluminum oxide formulation prevents “loading” on soft (non-ferrous) metals all sizes internally reinforced with the highest quality fiberglass for maximum safety and performance our unique super-lock hub combines both a mechanical locking system and chemical bond providing one of the safest, vibration-free designs in the industry