Metal Bond Diamond Discs feature Diamond Particles Imbedded in a Metal Matrix on 8" Magnetic Discs or with PSA Adhesive Backing. A hard nickel alloy is used to rigidly bond a layer of sharp, blocky diamond to a steel backing.  The sharp diamond particles cut cleanly with no edge rounding. Unlike other brands, exposed diamonds do not affect diamonds already working on material, they remain sharp and get sharper prolonging disc life with more consistent results.