Abstract: A coupling mechanism securing a first object having a well to a second object having a lug, including a shuttle movable within the lug, a resilient biasing means biasing the shuttle away from a base of the well when the lug is inserted, and locking elements movable radially in the lug between a retracted position and an extended position. Each locking element moves from the retracted position and retains in the extended position by a surface profile of the shuttle. The coupling mechanism includes a movable stop having: a first position in which movement of the shuttle is limited so the locking elements interact with the surface profile, and a second position in which movement of the shuttle is extended to cause the locking elements to interact with another surface profile of the shuttle, moving the locking elements from their extended position to their retracted position.