Chances are, the one time you need your torch the batteries will have died. But not with Lumen.
That's because it doesn't take batteries. Instead, it's powered by the warmth of your touch.
It features a thermoelectric generator – basically a small ceramic bar – that produces a current when you place your thumb on it. The difference between your body temperature and the environment is enough to power a single LED.
When the difference is bigger – you're extremely hot, or the environment is extremely cold – the excess power is stored for later.
It's about as bright as the torch on your smartphone. But obviously it won't drain your phone battery, and will last forever.
So how do you find it in the dark? It has a tritium vial – a glass tube – inside which is a layer of phosphor and tritium gas. It generates light for more than a decade, so you'll always be able to find it. It's also available without the tube, if you want to pay less.
Not only will it never die, it's also better for the environment.
The $30 early bird has all gone, so it'll cost you $35 (£23). It's already passed its funding goal and will ship in February.