To help divers rapidly gauge how long they've been underwater, the bezel is often marked with minutes up to 60. While underwater, you may check the time remaining in your dive by rotating the bezel until the zero mark is at the minute hand. In addition, the bezel usually only spins in one direction, so any unintentional movement would only reduce your dive rather than lengthen it and push you over your no-decompression restriction. The bezel is, in short, always for your ease.