Diamond Radius and Spherical Surface Grinder Grinding Wheel made with a light weight wheel featuring a seamless steel rim has a 1" arbor with bushings to bush the arbor to 3/4", 5/8", and 1/2".It is a fantastic tool for both removing punty marks and carving designs and lenses into your work. Placed into a bench grinder this wonderful little tool is limited only by your imagination with what it can accomplish for you. They provide a high visibility at the point of contact and are excellent for the quick removal of punty marks. Grit 60-600#