DAMO 4" Diamond Turbo Grinding Cup Wheel Coarse Grit for Concrete / Granite Floor Super aggressive due to the Multilayer Vacuum Brazed Tech.; Balanced by Dynamic Balancer; Swirl turbo segments for quick cooling of the working cups; Coarse type 30/40,used on grinders with 5/8"-11 spindles; Use dry or wet, maximum speed 11,000RPM.