Each brush has a 1/4" hex driver shank. 1/4" driver handle with quick lock adapter. 12 steel, 12 Brass and 12 Nylon. Brushes are made of stainless steel, brass wires and nylon. Included in a protective blow molded case Cleans bushings, ports, tubes, holes, channels, sockets, brake guides, and much more! This 36 piece set of bore brushes are made of twisted steel and brass wires for optimum performance at low speeds. The sizes include 8mm through 19mm. Also comes with a 1/4" driver handle for a better support and grip!