Rhodius 210046 Steel Grinding Wheel, RS2 Series, PROline Quality. Type 27 Wheel, 4-1/2 inch Diameter, 1/8 inch Thickness, 7/8 inch Arbor, 13285 rpm Maximum Speed. PROline products have been designed for very high quality demands and frequent use in industry and trades. They offer a good price-performance ratio and a high efficiency.