Black Diamond's latest innovation on the headlamp scene was designed to be the smallest lamp in existence, while providing adequate light for climbing and backcountry use. With two super-bright LEDs and a featherweight adjustable headband, this lamp can be adjusted to fit over a helmet, beanie or hat. When placed in a shirt or chalkbag pocket, its presence is barely detectable; however, once the Ion is put to use, its full functionality becomes immediately noticeable. Runs on one six-volt battery that's included with the lamp