SI FANG is an innovative company focusing on producing cost-effective premium tools and accessories tools. We wish to help our clients improve their productivity by using our durable and affordable tools. We cares about customer's feedback, and are willing to hear your voice to make our products better to meet your needs. Material: Constructed Of Industrial Grade High Density Premium Zirconia Aluminum GrainScrew Thread: Resin Fiber With A Fiberglass Backing Plate To Offer Extra Strength And Absorb Vibrations Not Easy To Fall OffDesign: Grinding Disc is Semi-open To Reduce Loading On Aluminum Surfaces Great For Grinding, Blending, Sanding And Finishing On A Wide Range Of Material,such As Rust, Paint, Ferrous, Stainless Steel, And Non-ferrous Metals, Wood And Plastics Product Specifications SIZE 50mm (2 Inch) MANDREL 6.35mm 1/4 Inch GRITS 40 60 80 120 Grit ABRASIVE Zirconium Alumina FLAP: Cotton BACKING MATERIAL: Extra Heavy Duty Plastic ATTACHMENT: TR MAX.RPM: 14000 This flap disc set is featured with a torque spiral on the back for inserting the sanding disc pad holder more tightly, which ensures your safety while using, as well as to change the discs quickly for more efficient work.