Metabo Depressed Center Wheel, Type 27 General Purpose Universal, Series Original Cutting, 6 in dia, 18 in Thickness, 78 in, A30R Grit, Coarse Grade, Aluminum Oxide Abrasive, 10200 RPM Maximum, ResinResinoid Bond, Applicable Materials Steel and Ferrous MetalsThe Quality of Cutting and Grinding Wheels Depends on Several Factors The Grain Size, Shape and Quality Determines How Aggressive a Wheel Is The Right Mix of Bonding Resins, Additives and Fiberglass Reinforcement Determines The Wheel Life Metabo Cutting and Grinding Wheels are Designed and Manufactured in Accordance With Our Most Stringent Specifications So That They, in Combination With Our Power Tools, Achieve The Best Performance and Productivity, Saving Time and Money