a web structure defining an essentially tubular body having a tubular wall with a longitudinal axis and a circumferential diameter, the web structure being expandable from a contracted configuration to an expanded configuration;

a plurality of longitudinally adjacent circumferential web patterns defining the web structure;

each web pattern being defined by a plurality of sequentially adjoined webs, the plurality of sequentially adjoined webs being disposed circumferentially around a longitudinal axis of the essentially tubular body; and

at least one connection element extending between and connecting adjacent pairs of the web patterns configured to shorten and/or lengthen along the longitudinal axis within a curved plane defined by the tubular wall in the contracted configuration and/or the expanded configuration, the at least one connection element being formed by three connection webs, at least two being substantially non-parallel relative to one another and at least two being substantially parallel to one another, the three connection webs being disposed at an angle relative to one another, a rounded notch reducing a dimension of the connection element being formed at the junction of adjacent connection webs and at least one rounded notch disposed between a proximal end and distal end of the connection element.