This 4-inch knot wheel stringer bead brush features twisted 302 stainless steel wire for removing weld scale, corrosion, paint, and other buildup. Its durable hub, high-tensile-strength wire, and resistance to wire breakage support dependable use at speeds up to 20,000 RPM; it has a 0.020-inch thickness and a 5/8-11 arbor. **California Proposition 65 warning:** This product can expose you to nickel, a chemical known to the State of California to cause cancer. See https://www.P65Warnings.ca.gov.