Arc AAA UV
This is an UV (Ultra Violet) edition of the Arc AAA. It features a Nichia NSPU510CS 375nm UV LED powered by a single AAA battery, it can use lithium, alkaline or nimh rechargeable AAA batteries 1.5v.
The body is constructed from Type III Hard Anodized 6061 Aluminum and the interior is coated with chemkote for stronger corrosion reistance.
The switch is a twisty at the head, twist the head for simple on-off activation, o-rings make the light water reistance up to a hundread feet. Runtime with an alkaline battery is about 5 hours to 50% power.
UV lights are useful in many applications where objects need UV wavelengths to flouresce, like detecting counterfeit, scorpions, body fluids and others. Exposure to UV light is potentially harmful to the eyes so this is not a light to play. If you need a keychain UV light the Arc is probably one of the most durable versions you can get it will last forever in your keychain. If you don't need a very rugged light you have several options much cheaper and with similar runtime and output so this one probably makes sense only for those that use an UV light every day.
You can get it for $40 at ArcFlashlights.