Essentially it's an everlasting light source that is always with you.
From their Kickstarter Page, to quote:
WHAT IS LUMEN?
It is an ordinary flashlight with brightness comparable to your smartphone's except his main feature - it doesn't need batteries and virtually eternal.
HOW DOES IT WORK?
Lumen has relatively simple work principle - you touch TEG (Thermoelectric Generator) - small ceramic bar that can produce electric current when we provide temperature difference between upper and lower parts of TEG.
In my application difference between temperature of your body (about 98 °F) and environment (at least 82 °F) is enough to generate power for single led. Metal body of Lumen serve as a radiator.
- Weight : ~ 35 gramms \ 1,2 oz for Aluminium version
- Weight : ~ 45 gramms \ 1,5 oz for Titanium version
- Dimensions: 40 mm x 10mm x 80 mm \ 1,6" x 0,4" x 3,2"
- 5mm ultrabright CREE led
- Light output: 3000 mCd