Dually 7″ Root Pass Weld Cleaning Brush features a dual-hex nut design that simplifies periodic flipping of the wheel for maximum cleaning action, long life and safer use. 5/8″11″ double hex nut for use on right angle grinders. Feature a dual-hex nut design that simplifies periodic flipping of the wheel for maximum cleaning action, long life and safer use. Narrow face brushes are suitable for cleaning root and hot passes and reaching into corners. Tool: right angle grinder. . .