Pearl's depressed center grinding wheels are especially well suited for grinding, weld dressing and deburring. Pearl depressed center wheels are engineered for aggressive stock removal and extra long life. All wheels are fully reinforced and meet or exceed US/Canada safety standards and specifications. Pearl’s Fine-Grit Back Layer Improves Grinding Action! Our Fine, Hard Back Depressed Center Grinding Wheels feature a finer-grit mixture in the top half of the grinding wheel that limits premature shedding or “spalling” and allows for a smoother grinding action from start to finish.