being designed such that it is linearly in contact with an inner wall of the outer tube application_number US 201514813583 A description referring to the drawings fig1 shows a first exemplary embodiment of a coaxial type tube system in a longitudinal section while fig2 shows the cross section of this tube system it can be seen in these two views that the tube system has an outer tube 1 and an inner tube 3 and the outer tube 1 has a symmetry axis 5 and the inner tube 3 has a symmetry axis 7 these two symmetry axes 5 7 are located at spaced locations from one another so that the inner tube 3 is arranged eccentrically in the outer tube 1 the outer tube 1 has folds 9 with two flanks 11 13 each which spread out during the extension of this variable length tube system in addition to the folds 9 the outer tube 1 has in this embodiment a groove like profile 15 which extends circumferentially around the outer tube 1 and which is connected to a profile 19 extending circumferentially around the inner tube 3 on the radially outwardly directed outer side 17 of the inner tube 3 by locking in a positive locking manner this positive locking connection of the profiles 15 19 may be repeated several times at preset spaced locations over the entire length of the tube however these additional possible connection points of additional profiles 15 19 are not shown in the detail view of the tube system which is shown in fig1 just like the outer tube 1 the inner tube 3 has folds 21 in the exemplary embodiment being shown here for changing the length these folds being formed from two flanks 23 25 which.