Casio's Bluetooth F-B100W-1A with step-tracker sells out again, leaving only the F-B100W-3A

Casio's black F-B100W has sold out on the brand's UK store, nearly a week after going on sale. However, the teal F-B100W-3A is still available at £55.

The pattern is similar to what happened in Japan. The series launched there on 7 August at ¥8,800 and cleared Casio's official store the same day. Casio UK listed both references as coming soon shortly afterwards, opened sales on 17 August, and has now completely exhausted the black variant.

Casio has not said whether the reference will return. Plus, the sell-out applies only to its own store and not third-party retailers. Additionally, a third variant with a negative display, the F-B100W-1B, never even showed up on the UK site.

The £55 asking price is the interesting part. Converted at current rates, the Japanese figure works out at about $55 against roughly $74 in Britain. Both include local tax, at 10 percent in Japan and 20 percent in the UK, so subtracting that still leaves the British price around 22 percent higher. A standard F-91W (curr. $25 on Amazon), meanwhile, sells for about £20.

What the premium buys you is a motion sensor. The watch counts to 999,999 steps, displays progress against a daily goal on a six-level graph, accepts targets between 1,000 and 50,000 steps, and can prompt the wearer after long periods of inactivity. Bluetooth pairing with Casio's Watches app handles automatic time setting, roughly 300 world time cities and activity logging.

The case has the F-91W's proportions at 41.9 by 38.1 by 8.8 mm and 26 grams, with an LED backlight, stopwatch, countdown timer and five daily alarms. Casio rates the CR2016 cell at approximately two years, against the seven the F-91W is known for.