Abstract: An apparatus for determining lengths of locking elements in locks including a key head and wires maintained on the key head and extendable into the lock cylinder for measuring lengths of the lock pins. The distance that the wires will go into the depth of lock can be used to determine the depth of the furrows or the cuts of the needed key. The advantage of this invention is that one can duplicate a key which has been lost, without damaging the lock, or moving it out of the door. In addition to that this mechanism is also used as a "lock-picker" in order that one can lock or unlock a door when the keys have been lost. The invention operates in two different ways and for two different purposes. The first one is to duplicate a key which has been lost. The second one is to lock or unlock a door for different reasons, e.g. when the key has been lost, or when it is still inside the car or the house while the door is still locked.