The light duty of ladder truss,triangle truss,square truss have standard size,such as 250*250mm,300*300mm.The medium-dutytruss have 400*400mm,450*450mm,500*600mm.The heavyduty truss have 520*600mm,600*760mm,520*1000mm have two connector ways:one is square connector,another is aluminum board connector,it made of the diamiter 50mm as main tube,and diamiter 30mm as inside tube beside the light -duty used diameter 20mm which have large loding capability for used in heavy project.