Normally, the small dial inside a watch is called a "sub dial" and its main function is to assist the watch in providing some time information. Generally, there are Chronograph, alarm clock, calendar, etc. Most watches have three small dials, and each dial has a different function and timing. The small dial at three o'clock represents the hour, the small dial at six o'clock represents the record of the second hand, and the small dial at nine o'clock represents the record of the minute.

Many people think that a watch with three small dials on it looks very complex, and they don't even know which one corresponds to what. But only by understanding the mystery inside, is it actually not so. To take a simple example, if the small dial representing the second hand is engraved with 60 Arabic numerals, then this dial indicates that there is a 60 minute totalizer; on the contrary, if only 30 is engraved, then it means that a circle represents 30 minutes. The use of other dials is the same. For example, if the top of the record table representing hours is engraved with 12, it represents the count of hours. And when the minute dial starts to move, the dial representing the stopwatch will also follow, which is the same as when we usually look at a watch.