25 Pack, 9 in. 150 Grit (Fine) Drywall ROS Hook & Lock Discs. Diablo's Premium Drywall Sanding Sheets Include Break-Through Innovations That Improve Performance, Extend Sanding Life And Increase Productivity. Featuring A Premium Aluminum Oxide Blend, These Sheets Deliver Smooth Finishes, Faster And Offer Extra-Long Sanding Life Than Other Sanding Sheets. Clog-SHIELD, Diablo's Own Blend Of Grinding Agents, Reduces Loading Thereby Maximizing Productivity When Sanding Drywall, Mud, And Plaster. The Superior Grain Bonding System, ENDURA-BOND, Provides Diablo's Sanding Sheets With Longer Life And Extreme Durability. These Sanding Sheets Are Ideal When Sanding Medium To Large Surface Areas.