Abstract: A locking device for controlled, reversible security using a control key to set the lock's accessibility to multiple individual keys, thus providing complete control of security. The control key has hierarchy over the individual key(s). Rotating the control key from the first to a second position prevents the core from being actuated by the individual key(s), thus activating a blocking function by which the lock can only be operated by the control key. Returning the control key from the second position back to the first position allows the control key to be removed ( the blocking function is still active). When the control key is rotated from the first to a third position, the core can be operated by the individual key(s), thus inactivating the blocking function. Returning the control key from the third position to the first position allows removal of the control key (blocking function remains inactive).

Abstract: A locking device for controlled, reversible security using a control key to set the lock's accessibility to multiple individual keys, thus providing complete control of security. The control key has hierarchy over the individual key(s). Rotating the control key from the first to a second position prevents the core from being actuated by the individual key(s), thus activating a blocking function by which the lock can only be operated by the control key. Returning the control key from the second position back to the first position allows the control key to be removed ( the blocking function is still active). When the control key is rotated from the first to a third position, the core can be operated by the individual key(s), thus inactivating the blocking function. Returning the control key from the third position to the first position allows removal of the control key (blocking function remains inactive).