(1) This is the center main shaft with adjustable function composed of steel and aluminum 6061 T6(2) The steel wire ring is secure to hold the screws fix in position prevent from falling out (3) The aluminum shaft body is light in weight and strong (4) The adjustable length of the shorter one is 100mm to 107mm and 135mm to 142mm for the longer one (5) Multiple colors are available for selection(6) We offer worldwide delivery by DHL and free local delivery by SF Express ACCESSORIES:2.5XM4X11SCREW SHAFT X 4PCS