https://www.amazon.com/Compact-Lumens-W ... B013CQ1OYY
For backpacking almost all of us carry a headlamp for reasons that need not be explained in this knowledgeable user community. However it is one of a few key items where some kind of backup provides important safety like a second Bic lighter or pair of eyeglasses. The notion of bringing two headlamps would add unnecessary weight while a really small spare flashlight weighs little. The waterproof bombproof aluminum body E01 is minimally larger than a single AAA battery that powers it and weighs just 14 grams sans AAA.
There are smaller LED flashlights than the E01 that use coin button batteries but light outputs are sure to be weak as battery cell capacities are much less than an AAA. Additionally coin button batteries are not rechargeable and if lithium, expensive to toss. The E01 uses a voltage regulating IC that provides a constant 13 lumen brightness regardless of how much an AAA has run down as long as it is above a minimum threshold. That regulation also means there is not the usual cheap flashlight brightness level advantage to using an alkaline battery (new 1.65volts) versus a charged NiMH (charged 1.2 volts) given similar capacities. Nor does the light dim as the battery gradually discharges.
I own 4 of the E01's in different colors and use high capacity NiMH batteries of which I have dozens of both AA and AAA. Out in the backcountry one is always in my daypack and back at home or hi tech workplace, one is always in my pocket. There is a hole at the end of the aluminum body one can push a cord through in order to make a wrist loop that can be especially functional in the dark. Slipped around one's wrist inside a tent where bears may visit, it provides a certain readily available light source when one suddenly wakes up by spooky sounds of twigs breaking nearby.
David
http://www.davidsenesac.com/2016_Trip_C ... les-0.html
