The Arc AAA is a small, LED flashlight produced by Arc Flashlight, LLC (now out of business). It is only slightly larger than the AAA battery it uses, and is made of solid aircraft-grade anodized aluminum. It is extremely bright, has excellent battery life and uses a high quality white LED.
Arc AAAs are water proof. They have been emmersed in liquid nitrogen, been taken up and down Mount Everest and been rolled over by tanks without losing their functionality.
The exceptional battery life of the Arc AAA has a lot do to with the built-in voltage regulator. In order to keep the voltage constant, the regulator increases the current draw on the battery if there is a voltage sag, maintaining a constant amount of power being drawn from the battery. And, as we all know from the physics, IV = IV, power in equals power out. The regulator works so well that "dead" batteries from things like remote control units will provide approximately three hours of good brightness from an Arc AAA.
Now that Arc Flashlight, LLC. is out of business, it is difficult to find Arc AAAs (as well as all other Arc Flashlight lamps). They're available on eBay, but they're expensive; collectors really like bidding on them. Before the company went under, Arc AAAs cost about $30 American, ex-shipping.
I am lucky enough to have recieved an Arc AAA as a birthday gift. It lives on my keychain, where it continuously proves itself to be very, very useful. In almost a year of frequent use, it has yet to need anything beyond the battery it shipped with.
Thanks to Calast for pointing out that the Arc AAA is made with aluminum and not steel