These Type-R ZIRCONIA Abrasive Flap Discs come in grit sizes ranging from 40 to 120 density, disc size comes in 2-inch with quick-change connector. High quality imported German VSM ZIRCONIA alumina grain material offers better efficiency and durability. Variations in dimensions are designed for usage on a variety of surfaces: flat or contoured steel, stainless steel, wood, and more. Depending on grit size, they can be used for stock removal, beveling, weld blending, de-burring, blending, rust removal, and smooth finishing.High Density flap discs have 50% more abrasive cloth pieces and provide 100% higher performance compared to standard flap discs. The lightweight yet strong fiberglass backing plates on the discs reduce vibrations during usage for a smoother and more efficient work experience as well as an increase in durability and prevention from smearing. We have tested our flap discs on major brands of die grinders and on various types of material surfaces, including steel, stainless steel, alloys, and wood. We have also tested competitors' flap discs and found that Eco Edge's flap discs perform just as well as, and sometimes even better than, those of competitors.Before using any power tools, always read the user's manual and safety codes. For using flap discs, comply with ANSI B7.7 and use in a safe working area with the proper safety equipment, such as gloves, ear sets, dust masks, and eye protection. Always use a guard on the angle grinder and check the machine speed. Never use a damaged flap disc or exceed the specified maximum RPM.