I Tested 4 1 2 Grinding Discs: Heres What You Need to Know! 2 Pack 4 inch 100mm Angle Grinder Disc, Wood Grinding Wheel Tungsten 100x16mm 4'' Fibre Sanding Grinding Discs Wheels 24 120 Grit For Angle 3inch Grinding Wheels Cutting Disc Grinding Wheel Wear Resistant Angle 4 1 2" Flap Sanding Disc 40 60 80 120 Grit 4.5 Grinding Wheels for. About this item : Grit Material Aluminum Oxide Item Dimensions LxWxH 9. 45 x 8. 86 x 4. 72 inches Compatible Devices Angle Grinder Grit Number 120 Color redDescription: Size: Diameter is 4 1 2, Arbor is 7 8, the flap disc is standard size and suitable for most air and electric grinders. Specification: Type #27, the grinder sanding discs are better for smoothing and blending surfaces. Maximum speed 13300 revolutions per minute (RPM), the wheels perform well. Package contains: 40 60 80 120 grit angle grinder sanding discs, 10 x 40 grit, 5 x 60 grit, 3 x 80 grit, 2 x 120 grit, the combination better matches your requirement.