Weiler 3/4″ Knot Wire End Brush features a hollow end and heavy-duty brushing action with some flexibility for more demanding cleaning and deburring applications in recessed areas. 1/4″ stem diameter for use on CNC/milling/automatic machine, die grinder, drill, drill press, right angle die grinder and straight grinder. Hollow End and Heavy-Duty Brushing Action with Some Flexibility. Ideal for more demanding cleaning applications in recessed areas. . . .