I picked up one of these little guys at the recent SHOT Show. They are new for this year.
On the left is my Surefire E2E, the Nano is in the middle, and on the right is a generic LED keychain light.
The body is constructed of anodized aluminum, and it has a 100,000 hour life, high-intensity, 10 lumen LED. It is only available with a white light. It has an eight hour run time on four LR41 button cells. It comes with a snap hook.
It's an excellent light for its size. The output is bright and cool white, and perfect for short distances, as you can see in the picture:
It is a good light for those who don't want to carry around a lot of gear and who don't use a light much, or for those who want a little backup light. It's too small to use as a striking weapon, but the little booger wins in overall cuteness factor and ultra-compact brightness.
You should be able to pick one up for under $6.