Abstract: The key (1) for a lock (2), comprises at least a lever (9) having a first arm (10) for starting movement and a second arm (11) for activating a tumbler element of the lock (2), the lever (9) being pivoted to the shaft (4) of the key (1) with an oscillating axis thereof being transversal to the longitudinal axis of the shaft (4) of the key (1), the first lever arm (10) and the second lever arm (11) being located on a same face (5) of the shaft (4) of the key (1).