The invention concerns a collar with a tracheotomy cannula or tube, wherein the collar embraces a respiratory tube in sealing relationship. The collar comprises separate inner and outer films, the outer film being elastically stretchable. The collar of the device allows no or only small tight folds formed which do not affect sealing integrity between the collar and the trachea wall even at low pressures. The outer film is expandable to a diameter larger than the diameter of a trachea, and in particular is at least 1.5 times the outside diameter of the tube, and the inner film comprises a material of lower elastic stretching. The inner film is produced oversized and without an external restriction at an internal pressure of at most 20 hPa assumes a diameter which is larger than the diameter of a trachea.