<p>A universal lock and key assembly in which the lock is re-keyable and the key is also changeable. The key has a shank portion having a longitudinally extending tooth slot in its top surface. A plurality of teeth have their bottom ends inserted into the tooth slot in any desired sequence to give a predetermined profile to the teeth of the key. The bottom pin cylinder of the lock has mating bottom pins for each of the respective teeth. These are then arranged in a coordinated sequence in the bottom pin cylinder of the lock. The structure of the system allows an individual to change both the configuration of the key and also the mating structure within the lock so it will be operable.</p>
