Casio F-91W

Casio F-91W

The Casio F-91W has been in production since 1989 and has barely changed in that time. It’s one of the best-selling watches ever made, and it still costs about £15.

It weighs 21g, the case and strap are resin, and the battery lasts around seven years. There’s a daily alarm, an hourly chime, a stopwatch that times to a hundredth of a second, and a small light to the left of the screen for reading it in the dark, though it’s not a very bright one.

It’s splash resistant rather than waterproof, so it’s fine in the rain and best taken off before a swim.