... safe span, it should be reach 24M &load about900KG for one side when large span.4.They are both Aluminum quadrate and ... Aluminum truss.5.Bolt truss,All they are two series,one is light-duty truss ,such as 150*150MM,200*200MM ... ,250*250MM,300*300MM...,Another one is heavy-duty truss.like400*400MM,450*450MM,520*760MM ...