The earlier Double Tube was replaced by the Double Tube Connector. Instead of one fixed Double Tube, two standard Tubes are now connected with two Double Tube Connectors. This allows the familiar models to still be built while keeping the system more flexible, because the standard Tubes can also be used for many other constructions. The combination of two Double Tube Connectors and two Tubes is also significantly more stable than the earlier Double Tube solution from the 1980s and 1990s.
