Tommy Hilfiger Men&#39;s 1710157 Automatic Leather Strap Watch Quality automatic movement; functions without a battery; powers automatically with the movement of your arm Watch does not require battery to operate, watch powered by the movement of your arm Much like the pendulum on a grandfather clock, a counterweight inside an automatic watch winds its gears with the motion of a wearers daily activity If watch stops after a day or two of non-use, wind the crown and give it a gentle shake to start the movement again Water resistant to 99 feet (30 M): withstands rain and splashes of water, but not showering or submersion