Nauticalia

The gaseous tritium self-powered light sources used in these watches are much brighter than luminescent or phosphorescent paint, and never need re-charging from another light source. There's no fiddling about with buttons or worry about running the down; they will glow all night (and day, but you can't see it) for a guaranteed 10 years - and typically last 20. They were developed for the military but are also useful in civilian activities such as night sailing, camping, and diving. One division of the UK special forces was so impressed by its failsafe illumination system and tough construction that they ordered 300.