The Casio F-91W launched in 1989 as a simple, inexpensive digital watch and went on to become, by most counts, the best-selling wristwatch design in history — with production estimates running past 100 million units and roughly 3 million more added every year. The design hasn't meaningfully changed since: same resin case, same module, same three-button layout.

The F-91W-1JH is that watch, sold new today through Casio's current Japan lineup rather than pulled from vintage stock. It keeps the stopwatch, daily alarm, and 12/24-hour display of the original in a 21-gram case, at a price that hasn't drifted far from where it started.