Casio F-91W. The design has not changed for donkeys, they've sold many millions & the battery lasts years.
Wikipedia: "According to secret documents issued to interrogators at Guantanamo Bay, obtained and released by The Guardian,
"the Casio F-91W digital watch was declared to be 'the sign of al-Qaeda' and a contributing factor to continued detention of prisoners by the analysts stationed at Guantanamo Bay. Briefing documents used to train staff in assessing the threat level of new detainees advise that possession of the F-91W – available online for as little as £4 – suggests the wearer has been trained in bomb making by al-Qaeda in Afghanistan."United States Military intelligence officials have identified the F-91W as a watch that terrorists use when constructing time bombs.
Obviously, any other watch or device including a precise alarm can be easily modified for the same purpose by anyone with a basic knowledge of electronics. The F-91W simply happens to be a very popular, reliable, ubiquitous and inexpensive watch which is readily available almost everywhere in the world."
