A switch (1) which comprises a box-like body (2) which has a lateral containment portion (3) and an intermediate closure element (4) which has a through opening (5) and forms, with the lateral containment portion (3), an upper or actuation portion (6) and a lower or containment portion (7); the box-like body is associable, at its lower portion (7), with a shoe (8) which supports at least two fixed contacts (10) and at least one connector (11), which is mounted so that it can move between a first stable condition and a second stable condition and is functionally connected to an actuation element (12) provided with a respective spring element (13), which is accommodated within a containment recess (14), and is functionally connected to the connector (11) and has, on the opposite side with respect to the containment recess (14), an abutment body (15) which is accommodated substantially at the through opening (5); means are also provided for forming a seal between the abutment body and the intermediate closure element (4), and the abutment body (15) has a receptacle (17) for a pin (18) supported by a key (19). The sealing means comprise a sealing element (100), which protrudes from the edge of the through opening and is elastically deformable in order to press against the abutment body.