Leaked files reportedly reveal a certain Casio watch was viewed with suspicion by US officials as a possible sign of terrorist links.

A cheap timepiece; they are water resistant and have a battery life of approximately seven years.

Now this unassuming, black, plastic, digital timepiece has found itself in the news for a different reason. Leaked US documents reportedly advised interrogators at Guantanamo Bay that possession of the F-91W could be a link to bombing by al-Qaeda.

The Guardian, which obtained the leaked files, reports that wearing one has been a contributing factor to the continued detention of some prisoners, with more than 50 detainee reports referring to the watch.

It's an unexpected twist in the tale of this unassuming timepiece, launched by Casio in 1991. The Japanese company was one of the first to produce digital watches, becoming famous for them in the 1980s, along with calculators and electronic keyboards.

The F-91W instantly proved popular, not least because it was cheap and reliable. The company does not release sales figures for the watch, but says it was - and still is - a "huge seller" all over the world.

It's the classic Casio shape, with three buttons on the side to use its features. These include a stopwatch, second timer, alarm and the option of an hourly time "beep".

 

The F-91W is used in bomb-making "It's simply the classic digital watch," says Simon Mellor of Retro Vintage Watches. "In the last few years there's been an increase in demand for rare editions, with frames that are green or gold instead of the usual blue. I think this is down to schooldays nostalgia. I'm 28 and I had one when I was younger. I loved it."

"It's cheap enough to be disposable but, unless you hit it with a hammer, it will never stop."