model gt-550ex capacity 55,000 kg at 3.0 m boom: 5-section, 11.1 m - 42.0m 5-section full power partially synchronized telescoping boom of round hexagonal box construction with 6 sheaves at boom head. the synchronization ......model gt-550ex capacity 55,000 kg at 3.0 m boom: 5-section, 11.1 m - 42.0m 5-section full power partially synchronized telescoping boom of round hexagonal box construction with 6 sheaves at boom head. the synchronization system consists of 2 telescope cylinders, extension cables and retraction cables. hydraulic cylinders fitted with holding valves. where to buy this product contact the manufacturer