About This Industrial grade zirconia alumina:Grinder flap disc is constructed of high-density premium zirconia which extends the durability than those normal flap discs do Size in 4 1/2:4.5 flap disc features outer diameter in 4.5 inches and arbor in 7/8 inches,fit most 4.5” angle grinders in the market Dish type 29:Dish type 29 allows grinding at 15-25 degree angles, convenient for angled surface.Fiberglass backing plate effectively absorbs vibrations without smear during usage, bring more stable & efficient grinding Usage:Flap discs are ideal for metal or woodworking, concrete grinding or finishing, stone smoothing or finishing and so on. 80 grit is suitable for Rust Removal/Blending 20 Pcs angle grinder flap disc:20 pieces of flap disc in 80 grit are enough for quite a long time once ordered Overview Grit Material : Zirconia Product Dimensions : 4.5"L x 4.5"W Brand : S SATC Compatible Devices : Angle Grinder Grit Type : Fine