Abstract: A rekeyable look includes at least one chamber housing a tumbler pin stack having a master pin disposed between the driver pin and the bottom pin. The bitting of a change code key inserted in the keyway displaces the tumbler pin stack containing the master pin such that the interface between the master pin and the bottom pin is placed on the shear line defined by the cylinder shell and plug. Rotation of the change code key aligns a first slot on the change code key with the master pin wherein the master pin is received by the first slot. The master pin is carried with the change code key on removal of the key from the keyway. A replacement master pin disposed in the first slot is inserted into the keyway with the change code key. Rotation of the change code key aligns the replacement master pin with the drive pin.