Abstract: A novel way of locking and unlocking an adjustment device for an artificial leg or arm makes it possible to perform an adjustment of the prosthesis, without necessitating disassembly of the prosthesis or the removal of the prosthesis from the patient. This facilitates the work in adjusting the translatory position and the angular position, and the adjustment device also offers a further degree of freedom by the addition of the possibility of distal adjustment. The novel combination provides a locking ring (40) on the adjustment head. The locking ring offers a stable, adjustable locking of the adjustment head against a coupling sleeve (50) on the stump, while at the same time fixing the translatory position of the prosthesis.