A locking device for a prosthesis comprising a locking mechanism that may be disengaged from the locking pin using a single hand, and that remains in the open position until the pin is removed. The locking mechanism of the present invention thus provides a secure connection that may be more easily removed than current devices. The current invention comprises a self-holding release mechanism that makes it possible to use both hands for pulling the amputation stump out of the prosthetic sleeve. The release mechanism is held in an open position by an interior locking mechanism. When the locking pin has come out of the locking mechanism, the inner locking mechanism will let the release device return and the lock will reset, and again be ready for use when the locking pin is inserted once more.