.Polyflex Wheel Brush, Encapsulated Small Diameter, 1-1/4 in Brush Dia, 3/16 in Face Width, 3/8 in Arbor Hole Size, Crimped Filament/Wire Type, 0.008 in Filament/Wire Diameter, Steel Fill, 5/16 in Trim Length, 20000 rpm Maximum, Unthreaded Arbor Attachment.