The light duty of ladder truss, triangular truss, and square truss has standard size as 250 x 250mm, and 300 x 300mm. The medium duty trusses have 400 x 400mm, 450 x 450mm, and 450 x 600mm. The heavy duty trusses have the sizes of 500 x 600mm, 520 x 760mm, and 520 x 1,000mm. The length is 0.5 - 4.0m. If the square truss overtop is 400 x 400mm, there are two connecting ways: one is square connector, the other is aluminum board connector. The main tube is made of Φ50mm, the inside tube is made of Φ30mm. The light duty uses Φ20mm, which has large loading capability for using in heavy project.