The Forney 72868 4-Inch Industrial Pro Double Row Twist Knot Cup Brush is a premium heavy duty double row twist knot tempered steel wire cup brush. Provides fast, efficient weld cleaning, paint, rust and corrosion removal of large surfaces. For best results and long life, apply light pressure and use the wire ends only. Use with medium sized high speed angle grinders. Forney Industries is one of America's longest operating family-owned metal working product companies. Founded in 1932, Forney offers more than 5,000 products for the hardware, automotive, farm and ranch and do-it-yourself markets. 4-Inch (101.6-mm) by .020-Inch (0.508-mm) with 5/8-Inch - 11 threaded arbor. Max 8,500-RPM. Proof of purchase required. neglect, negligence or accident, or that has been used in any way contrary to the purpose intended.