This 4-inch knot cup wheel is designed to remove rust, scale, paint, burrs, and corrosion, and to clean and prepare large metal surfaces. Its high-tensile-strength wire resists breakage, while industrial-grade construction supports durability and a long working life; it has a 5/8"-11 arbor and a maximum speed of 8,500 RPM. **Warning:** This product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.