... 1.Material:Aluminum 6063 or 6061 2.Surface treatment:Anodizing high quality aluminium square tube 1.Material: AL alloy 6000 series, 3000series, 5000series ... : Silver,Golden,Black,Red,Blue and so on Advantage:1).Precision machining and cutting: length tolerance can be 0.2-0 ... same factory to ensure to the good quality and lead time.3).All OEM is welcome. all kinds of high quality aluminium square tube