1,different truss 2,aluminum truss 3,different size 4,have a long history bule cover truss,roof truss,aluminum truss Material size details ... , 400*400mm ,300*400mm etc.screw to connect the standard aluminum alloyFrame :4,3,2Type: 4,3,2.Material ... : Aluminum 606,160,636,082Head (diameter * thickness): 50 * 3mmInclined tube (diameter * ...