For years, standard key-ring flashlights used incandescent bulbs powered by one AAA alkaline battery. The durable, water-resistant MagLite Solitaire (*Est. $10) is still available, but flashlight reviews say it can't compare with the tiny Photon Micro-Light LED flashlights. They produce about six times the total light of the MagLite Solitaire, but weigh less than half as much and are smaller than a quarter. Both flashlights carry a lifetime guarantee, but while the MagLite carries a spare bulb in its tail, the LED on the Photon Micro-Light flashlight is unbreakable.
Flashlight enthusiast and reviewer Daniel Rutter of Dansdata.com calls the Photon Micro-Light "the best single LED light in the world if you want something really, really small." All the Micro-Light models use a high-output 5mm Nichia LED powered by tiny 3-volt lithium-ion "coin" batteries (*est. $3). FlashlightReviews.com estimates that the Photon Micro-Light Freedom (*Est. $20) can throw light about 23 feet, but of course these tiny flashlights are designed for closer use -- to read a map, find a keyhole or follow a footpath.
The Photon Freedom Micro-Light is the model reviews recommend most, since it has a microprocessor that lets the user adjust brightness. Reviews say that it's bright enough for short walks, yet can be dimmed for use next to a sleeping partner. In addition, four strobe-light options provide light that's visible up to a mile -- useful for summoning rescuers while prolonging battery life. It comes with both a quick-release key ring and a lanyard with a rotating magnetic clip. When clipped onto a hat brim, the Micro-Light serves as a small headlamp. Photon says the white-LED version gets up to 12 hours of battery life even at the brightest setting, but earlier reviews say it gets significantly dimmer after three or four hours -- though it provides some usable light far longer.
The Photon Micro-Light II (*Est. $16) has just one brightness level, while the Photon Micro-Light I (*Est. $10) has to be squeezed to stay on. The budget model, the Photon X-Light (*Est. $8) is made in China, but reviews say it's still better than knock-offs made by other brands. One review notes that the light from the X-light is slightly less even than that of the Micro-Light flashlights, but gives a nice broad beam for walking at night.
The newest model, the Photon ReX (*Est. $30) isn't reviewed yet at any of the big flashlight-review sites, but we did see a preview at BackpackingLight.com, plus some owner-written reviews. The Photon ReX provides brighter light with four LEDs instead of one -- and uses rechargeable batteries that lower the lifetime running costs. The rechargeable lithium-ion batteries recharge from any ordinary 1.2- to 3-volt battery, so each charge costs only about six cents. Recharging it from an AA rechargeable NiMH battery brings the cost per charge down to less than half a penny. It takes about two hours to recharge the flashlight, and it can't be overcharged. A solar charger is in the works.
These are great features, but owner-written reviews at the Photon forum indicate that it may have some bugs to resolve. Some owners have trouble with the recharging system, and reports of battery life vary from four hours down to 15 minutes. It's also bigger (1.25 by 2 inches, about half an inch thick), though even with batteries, it still weighs only 0.66 ounces.