What is the function of the circular dial?

Sport watches are usually equipped with can rotate counterclockwise circle of the table, in addition to the decoration and modern concept, the symbol of the movement of life table circle on the convex granule and clear, easy to read Numbers, allows the wearer to accurate calibration diving and exercise time, is absolutely reliable. The outer ring only rotates in one direction, and even if it is accidentally rotated, the rest of the exercise time will only be shortened, rather than prolonged, ensuring safety.