Oris bc4 flight timer is a modern and very functional aviation timepiece the watch is equipped with oris 690 automatic calibre a modification of eta 2836 2 the movement performs 28 800 vibrations per hour and has 30 bearing jewels a 38 hour power reserve is available for the convenience of the wearer hands and indices are luminous for improved night time visibility oris bc4 flight timer displays two time zones simultaneously the second one is indicated through a sub dial at 3 oclock sub