I have carried the Fenix E01 AAA LED flashlight for a year or so on an everyday basis and have included one on my "survival keychain" along with a Victorinox Classic knife, whistle, firesteel, and some tinder in a Bison Designs spy capsule. The idea is to always have a few basic essentials in my pocket to help in a crisis.
But my Fenix HL21 headlamp uses a single AA battery. That left me with no options to trade batteries between sources if needed and I would need to carry two different spares. I looked at lot of other AA LED flashlights and discovered the Olight line and the i2 EOS model that fit the single AA niche. It is a much more powerful light than the Fenix E01 and has more features.
A quick list of specs:
Cree XP-G LED
Keychain hole designed for every day carry
Three output levels : Low (2.5 lumens - 60 hours) - Medium (20 - 5 hours) - High (75 - 1.5 hours)
Removable clip with allen wrench removal tool in the package
Flat end to allow for tail standing
1 x AA battery
Highly water resistant to IPX-8
Premium Type III hard-anodized anti-abrasive finish
81.2mm x 17.6mm
My jewelry scale read 20.7g (0.73oz) without a battery. A Duracell alkaline is 24.5g(0.86oz) for comparison. It feels *light* in the hand. It has a removable pocket clip and comes with the tiny Allen wrench to handle the pocket clip screws. There is a stainless steel split ring on the end and it is mounted on the side so the light can stand on the end. The pocket clip or the split ring will keep the light from rolling too.
Changing light output modes takes a simple quick twist of the head. The light comes on in low mode, which I like: no blinding blast of light to rob all your night vision--- or raise the ire of your tent mates. 2.5 lumens is a very useable level for a tent light and the 20 lumen medium setting is fine for a latrine call and general use in camp or an easy trail. The high setting is very bright for dark adjusted eyes and as much light as I normally need. I was able to change modes with one hand. The light color looks very neutral to my eyes. I like the high beam pattern better than the Fenix HL21 headlamp, with a bigger center spot with softer edges.
The light is waterproof to IPX-8 standards, which the manufacturer sets at 2 meter submersion. The lamp came with two spare o-rings as well.
Retail is a reasonable $24.95. I found one on eBay for $19.50 including shipping.
I think this one is a keeper. It is light, bright, easy to use, waterproof, and has good battery life. It is not as pocket friendly as the little Fenix E01, but still pocketable and it has the clip option to help as well.
The photos showing beam pattern and relative light output are all done with the camera on a tripod and set on the same manual shutter speed and aperture and a medium gray carpet for the target.