Weiler 1-1/8″ Knot Wire End Brush features a hollow end, heavy-duty brushing action with some flexibility for more demanding cleaning and deburring applications in recessed areas on steel parts. 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. For use with die grinder, drill, drill press and right angle air die grinder power tools. Hollow End and Heavy-Duty Brushing Action with Some Flexibility. .