Double interlocking flexible conduits made from a helical ribbon of Sendzimir continuous hotdip zinc coated strip (UNI EN 10346 standard). They are extremely flexible and have an excellent mechanical resistance particulary when subjected to stress resulting from traction, torsion and impact. The coils are packed in cartons. It is necessary the use of the accessory cod. 66BOTT bushing of brass to replace the nylon bushing normally supplied on connectors.