roller 97 is equal to the diameter 2r of the roller 96 the depth d of the groove is at least equal to the maximum diameter of the optical waveguide for example approximately 2 mm the embodiment shown in fig1 and 17 is particularly suitable for use as an extension line in this embodiment a 1 piece molded element 130 has a plurality of molded disks 132 133 134 135 136 and 137 thereon arranged in two columns and three rows at the edge of the element 130 are recesses at which clamping devices 138 139 140 141 142 and 143 are located the optical waveguide is mounted at one of these clamping devices at the respective entry and exit points of the element 130 the clamping devices 138 and 143 are centrally disposed along the narrower edges of the element 130 with a recess extending therebetween esentially dividing the element 130 in half the clamping devices 139 and 141 are disposed on opposite sides of the element 130 as are the clamping devices 140 and 142 with recesses extending between those respective pairs of clamping devices bounded on each side by one of the disks between any two oppositely disposed clamping means therefore a path for the waveguide exists and between any two adjacent disks there exists a region at which the guide grooves intersect after the waveguide has been inserted in the guide grooves and wound around as many of the disks as needed the unit may be covered by a cover plate 131.