The case diameter of a watch — essentially the diameter of the watch face and its border, sometimes including any knobs on the side — is one of its most varied features. Ranging from very small to very large, the case diameter allows you to have bigger numbers or more datakeeping features on the watch. Women’s watches tend to have smaller case diameters while men’s watches are larger, but there are advantages to getting a larger diameter no matter your gender.

The wider the diameter, the wider the face, and thus the more room there is for additional features and designs. When looking at case diameter 55mm is among the bigger diameters currently available, and these watches can have calendars, moon phase calculators, and a host of other widgets. If you really want to have a information-packed watch, the larger diameters are the ones to look for.

When looking at case diameter 55mm or thereabouts allows for much larger numbers on the face, which is a blessing if you don’t have the best vision. Thicker, more prominent hour and minute hands are also possible with a wider watch face. Smaller watch faces are often crowded and require looking at the watch face very closely, which is not always something you can do while driving or while in a meeting at work.

The bigger the case diameter and watch face, and the bigger the numbers, the better the clarity if the numbers glow in the dark. Smaller numbers could appear blurry even to people with fine vision, but larger numbers are nice and clear when the lights are out and the glow-in-the-dark feature takes over. For example, the Seiko Men’s Kinetic Watch has enough room to have widely spaced numbers that glow gently and remain highly readable.

Don’t let yourself get into a situation where you can’t see your watch or tell what time it is. Look for large watches with big case diameters for easy reading.