The disclosure relates to a holding frame, into which plug-in connector modules can be inserted, wherein the holding frame is composed of two halves connected to each other, a first half and a second half, wherein, for the purpose of opening the holding frame, the halves can be brought into an angular position less than 180°. The holding frame has at least one spring element that exerts a restoring force upon the halves, as a result of which lateral parts of the holding frame are brought back into a substantially parallel orientation in relation to each other.