PFERD's This premium cut-off wheel provides fast cutting performance and long service life. Recommended for professionals cutting steel and cast iron. Best selling cut-off wheel for steel are globally recognized for their fast, free cutting performance and excellent service life. Specification: Diameter (Inches): 4-1/2; Thickness Nominal (Inches): 3/32; Thickness Metric (mm): 2.4; Thread Size: 5/8-11; Max. RPM13,300; Abrasive: Aluminum oxide A; Depressed Centre: Type 27.