Wood Hub Wheel Brush, 2 Rows, Converging, Overall diameter 1 7/8" Wood Hub Wheel Brush, 2 Rows, Converging, Overall diameter 1 7/8" consists of Chungking bristles mounted into a hardwood hub with 1/4" arbor holes to fit tapered spindles of polishing motors. Wooden Hub diameter is 7/8", Trim length is 1/2". Bristle tufts are "staple-set" into wood hubs to remain securely fastened.