Casiotron TRN-50ZE-1A

In 1974 Casio made its first wristwatch, and the Casiotron did something no watch had done: it knew how many days were in the month. Every other watch of the era needed resetting on the first. Fifty years later this reissue keeps the original's proportions almost exactly — 39.1mm across, and marginally thinner — while adding solar charging, radio time correction and Bluetooth. The same watch, and an entirely different one.

Movement

Tough Solar quartz digital, Multi-Band 6 radio reception, Bluetooth

Case

Stainless steel

Diameter

39.1mm