Diablo Steel Demon 4-1/2 In. Type 27 HUB Metal Grinding Disc. Diablo's Steel Demon Metal Grinding Discs Deliver Industrial Performance, Increased Productivity And Longer Grinding Life. Featuring A Premium Ceramic Blend That Delivers Up To 6X Longer Life. A Fully Reinforced Depressed Center Enables The Disc To Withstand Heavy-Duty Metal Grinding. These Discs Are Ideal For Working In Hard-To-Reach Areas.