Aluminum, smooth surfaces, clear thread, not easy to corrode 1 / 4Inch connectors light Poles extension header, carbon fiber tube aluminum pipe connectors Only is 1 / 4 female & 1 / 4 male screw fittings, aluminum tube, aluminum tube, carbon fiber tube fittings are not included Can be used for 9mm inner diameter aluminum tube, carbon fiber tube Small size and light weight, easy to carry and use