What do the small clocks on a watch mean?

What the small clocks on a watch mean will vary from timepiece to timepiece. Called sub-dials, they serve as tools for measuring and tracking things other than the current time. Some common types of sub-dials include chronograph stopwatches for tracking seconds and fractions of seconds, moon phase trackers, power reserve monitors, second time zone dials, speed calculators and distance trackers. Explore a wide range of watches on 1stDibs.