Black Diamond, 50 LB, Medium, Blend Coal Slag Sandblasting Abrasives In Black/White Bags, Superior Cleaning Ability, Thanks To Hard, Angular Particles That Enhance Speed & Cutting, Low Free Silica Content, Low Dusting & Consistent Uniform Weight, Chemically Inert Hard Angular Pieces Enhance Speed & Cutting Very Low Friability Means Less Fracturing Or Splintering Consistent Uniform Weight & Gradation Ensures No Clogging Low Heavy Metals.