Wolverine 3/4″ Knot Wire End Brush features hollow end construction and heavy duty brushing action. Ideal for more demanding cleaning applications in recessed areas. 1/4″ stem diameter for use on die grinder, drill and drill presses. Solid end construction and flexible brushing action. Engineered to provide cost-effective use for less demanding applications. For use with die grinder, drill and drill press power tools. Hollow End and Heavy-Duty Brushing Action with Some Flexibility. Ideal for more demanding cleaning applications in recessed areas.