Coupling for a load carrier system with a tensioning member

The coupling has a fixing unit (23k) including a clamping element (72k) movably mounted at a plug retainer (17k) or a plug projection (63k), A clamping part (302) is displaceable between a clamping position and a releasing position by the clamping element. The clamping part is interlocked with a counter bearing (24k). The clamping part and the counter bearing are arranged at the plug retainer or plug projection on the outer side. The fixing unit fixes a fastening arm (51k) and a vehicle holder (13k) at each other.