All air components in a ventilation system has to be connected. This can be from Air Handling Unit to ductwork system, within a duct work system and from ducts to air terminal units. AHU and fans are connected to a rigid duct system with a flexible connector to avoid vibrations within the system . Rigid spiro ducs are connected with metal coupling pieces, reducers, T-pieces, collar saddle pieces, take-offs or bends. Flexible ducting are connected to rigid duct with a coupling piece or a take-off piece. Recangular ducts are connected to each other with profiles, corner pieces and clamps.