Casio F91W
The Casio F-91W is a quartz digital watch, manufactured by the Japanese firm Casio Computer Co., Ltd.. It was introduced in 1991. This watch is widely available throughout the world. Prices vary, normally in the range of US$7.50 to US$15. Casio does not release sales figures for the watch, but says the watch continues to be a "huge seller".
Read more about Casio F91W: Specifications, Operation, Claimed Use in Terrorism