Features: 1) Aluminum argon arc welding 2) Solid construction and safe 3) Easy to assemble Features: 1) Aluminum argon arc welding2) Solid construction and safe3) Easy to assemble4) Suitable for assembling lights, AV frames on stages and other exhibition places5) Models and length:a) Section 300 x 300 diameter: 3000, 6000, 8000, 10000, 15000b) Section 450 x 450 diameter: 3000, 6000, 8000, 10000, ...