Patent ID: 7260965

Claim:
A locking device comprising: a first key capable of converting a first lock into an opening state or a locking state; a second key insertable through a central key hole in the first key and capable of converting a second lock into an opening state or a locking state; the first lock including a first key inserting recess, and which prevents discharge of the first key from the first inserting recess in case that the first key is inserted into the first inserting recess and converts the first lock from the locking state into the opening state absent the second key; and the second lock including a second key inserting recess, and converting the first lock from the opening state into the locking state in case that the second key is inserted into the second inserting recess and moves the second lock between its locking and opening states, wherein the first key can only be discharged from the first inserting recess when the second key is inserted into the second inserting recess and both keys may be removed.