4" Knot Wire Cup Brush,.020 Carbon Steel Wire, Extra Coarse, 5/8"-11 Arbor, 9,000 Rpm, Designed For The Most Demanding Applications, Knot Wire Delivers Heavy Duty Impact Action, Excellent For Removal Of Scale, Corrosion, Rust, Weld Scale & Spatter, Forney Model #72327, Display Packaged.