At 3 ounces, the Swift RL Headlamp is Petzl's lightest, smallest light with Reactive Lighting. Catching attention from trail runniers, mountaineers, and mountain bikers, Reactive Lighting analyzes ambient light to automatically adjust the headlamp's brightness to the amount necessary in any given moment. It brightens up when you're staring down an extremely dark rappel, and dims down during sunset runs up sharp switchbacks. The Swift also has standard lighting options with flood, mixed, or focused beams. It comes with a battery that's rechargeable through micro USBs, and there's a five-level power gauge next to the port.