Tritium, a radioactive isotope of hydrogen, containing one proton and two neutrons, can cause phosphors to produce light, without consuming any other extern source of energy for years. Already used in watches, exit signs and self-illuminating gun sights for fire arms, it could be found even in keychain glow rings at DealExtreme.

Based on this phenomenon, this tritium keychain will glow for 10 years for only $1/year, without worrying about replacing batteries and even if it doesn’t glow as much as a common LED, this makes this cool gadget even greener than others. When you hear “tritium” you might think about nuclear radioactivity, but you don’t need to worry about any radioactive inconvenience, because the radiation is too low to cause any harm.

Via