You probably own a bike-light, chances are pretty good that you’ve got a headlamp, and it’s almost guaranteed that the batteries are dead in both. Bosavi is a hinged headlamp built more like a cell phone than a flashlight: it packs a rechargeable Lithium polymer battery and a chip that constantly monitors voltage, adjusting the power output to the LED on the fly for a constant brightness, up to a blinding 110 lumens. Bosavi also doubles as a bike light with the optional mount, and its packaging converts into a diffusing lantern.