A bi-stable microswitch (1) including a pair of contacts (4, 5) and an armature (10,11) movable between a first position and a second position to selectively break or make the pair of contacts, the armature being latched in the second position by a magnetic path including a permanent magnet (3) and a magnetizable element (7) having a first temperature, wherein the armature is resiliently biased towards the first position when latched, and is movable from the second position to the first position upon heating of the magnetizable element to above the first temperature.