... can adjust length within the scope of 1.17m to 4.39m at will, the short spine is used in ... 3,Support efforts Its supporting pole can put up 3-4 ton ,and the zone between two main beams can bear 2 ... -2.5 ton , and every sub-beam can bear 1 ton . Now the general thickness of ... smart lock connection between beams is simple and firm . No.4 : the horizontal pole is light and firm ,the smart ...