Velcro - The Diameter Of The Velcro Is 2 Inches And Is Suitable For Most Types Of Rotating Tools, Such As: B. Die Grinding Machines, Air Grinding Machines, Drills, Etc. Soft Foam Buffer Cushion - The Grinding Wheel Kit Contains A 1-Part Soft Foam Buffer Cushion. Make Sure That The Soft Foam Buffer Cushion Is Firmly Connected To The Grinding Discs And The Backing Plate Before Use. Quantity And Practical Set - Pack Contains 200 Pieces Of Grinding Wheels, 10 Grains, 20 Pieces For Each Grain: 80/180/240/320/400/600/800/1000/2000/3000 1 Pc 1/4 Inch Shaft Support Plate And 1 Pc Soft Foam Buffer Plate, Large Quantity To Meet Your Various Polishing Needs. Superior Material - Made Of Alumina Abrasive, Durable And Anti-Static, Useful For Cleaning And Polishing Corners, Such As Polished Metal, Wood, Jade And So On. Warm Note: These Grinding Wheel Pads Fit A 2 Inch Backing Pad, Which Is Not Suitable For Self-Adhesive Grinding Pads. Please Clean The Dust And Replace The Old Sanding Block Before Using It.