Arbor Mount Sanding Disc, Vacuum Hole Design No Hole, Disc Dia. 9-1/8 In., Grade Coarse, 50 Grit, Abrasive Type Closed Coat, Resin Bonded, Abrasive Material Zirconium Aluminum Oxide, Backing Material Fiber, Backing Weight X, Mounting Hole Size 7/8 In., Color Blue, Series F826, Max. RPM 6600, Package Quantity 25 Abrasive Fiber DiscsFull resin bond and fiber backing for strength, durability, and tear resistance. Use on right-angle grinders with back-up pads, sold separately on page 3718.4" discs have 5/8" arbor hole 4-1/2" and larger discs have 7/8" arbor hole Sold in pkg. of 25Bluefire F826Self-sharpening zirconia alumina abrasive provides fast, aggressive cutting action. Improved resin bond yields longer life. Suitable for stainless, alloys, and high-pressure use.