The Longines 343 watch movement is a gents automatic-family movement introduced during the period of 1949-1950. It features a ball-bearing rotor and underwent a simultaneous change from T- to U shock device, as well as a modified calibre, resulting in multiple variants. It is uncertain if all calibres were produced in the TC variant, with known versions being listed as UC. In addition, it has a detached manual wind mechanism, with further details found in the 1249UC variant. This movement includes the functions of automatic winding and a sweep second hand.