The Nano-Lux 10440 is a small AAA-cell sized mule that uses the new Cree XPL LED. A mule is a flashlight without an optic so it can produce a very wide beam with perfectly even illumination, they are extremely bright and work great as an area light. They have three outputs with a memory mode, and are offered in Electroless Nickel Aluminum, Brass, Copper, Stainless Steel and Titanium. The unit produces about 750+ lumens on the high setting with a smooth on/off twist head operation. The maximum power is produced from an IMR 10440, but a standard 10440 will also work, these torches will not work with an alkaline AAA 1.5 volt battery. THE TOP POWER SETTING SHOULD ONLY BE USED FOR SHORT PERIODS OF TIME BECAUSE OF THE SMALL HEAD DIAMETER AND HIGH OUTPUT LEVEL IT GENERATES LARGE AMOUNTS OF HEAT THAT COULD DAMAGE THE LIGHT. The settings are as follows: High-100%: Medium-30%: Low-5%. The unit will step down to a lower setting when the battery needs to be recharged. The flashlight has a length of about 2.65 inches and a head diameter of 0.60 inches, the battery tube diameter is 0.53 inch. A split ring is included so you can mount the flashlight on your keychain if you want. Price does not include batteries or a charger, and must be purchased separately.