There are lots of favorable photo-filled reviews of this light, along with a lot of unfavorable user reports claiming they break all the time, particularly at the battery wires. I think I saw a review saying they lack overvoltage protection too. The 1.0 version is rated 1 lumen (low) or 45 lumens (high), while the 2.0 version is 55 lumens high and claims to have something that sounds like LVP. Check Nitecore’s site for details. It claims 48h runtime on low (1 lumen) and I can attest that 1 lumen is plenty to find your way around in the dark with.
Anyway I didn’t want to pay $10+ for one of these, but illumn.com now has them on closeout for $5, so I added one to my most recent order and it came yesterday. It weighs just 9.6g according to the web site, one of the lowest weight lights I know of. The Photon Microlight and Freedom Microlight (introduced in 2005!) are around 7g and run on non-rechargeable coin cells, while the Tube has an internal lipo cell of supposedly 125mah (according to the Tube 2.0’s product page, assuming it uses the same battery as the 1.0).
My copy is in clear plastic so I can see some of the internal parts. It is held together with 4 small screws like the venerable Photon II and its Fauxton clones, so I have some chance of being able to get it apart (haven’t tried yet). The lipo cell does look soldered in, and I don’t know where I’d get replacements for less than the light cost. So maybe it’s disposable anyway.
I first tried charging it up from a power bank. The first thing I noticed was that when charging, an obnoxiously bright blue surface mount SMT led inside the light assaults your eyeballs, but you can always put something over it. The next thing is that my power bank shut itself off a fair while before charging was complete, since the charging load was so small that the power bank decided the load had been disconnected. I charged it the rest of the way on a wall plug phone charger.
The light seems to use a 5mm led. They are much brighter than they used to be, I guess. The beam is cool white with some spill, supposedly 45 lumens on high, and when freshly charged I’d guess maybe 2 lumens on low, reasonably smooth, and without the ghastly blue center of some older 5mm lights. There is a usable if somewhat annoying UI that gives brightness ramping (useless) and a lockout mode (hold button for 3 seconds) which seems useful. No blinking modes as far as I can tell, thankfully.
I generally find devices with internal batteries annoying, and they always seem to self-discharge when idle. This thing does manage to be quite small though, 7mm thick x 21mm wide x 56mm long. It’s one of the few lights I’d seriously consider using on a keychain (an AAA light is too big for that, imho). I remember stories of ultralight fetishists hiking the Appalachian Trail with just a Photon Microlight. This adds 2.6 grams but lots more flexibility, and the ability to recharge if you can get occasional access to a micro-usb phone charger, instead of having to derp around with replacing coin cells. That lets you use it somewhat more than you’d use a Photon. The 125mah lipo cell holds about the same the total energy of the pair of CR2016 coin cells in a Photon, and again, it’s rechargeable.
There is no pocket or hat clip for this minimal light, but you could stick some velcro on. They missed the trick of making the body from GITD plastic like the RovyVon A5X. That could have been useful since hanging this very small light on the outside of your backpack would work pretty well.
My main concern about bringing this as an “only” light would be its reliability. But two of them (one and a backup) still weighs less than a single 1AAA light with battery.
I have various reasons to not like Nitecore as a company, and I find some of their products ridiculous (a 4000 lumen, 8 ounce keychain light, really?). This particular model seems ok for what it is though, and a decent value at $5 or (new version) $10 for keychain use or as a gift (it comes on a retail card). For muggle use I’d suggest the 2.0 version because I bet a lot of 1.0’s died from lack of LVP.
Edit (2021-09-28): changed claimed battery capacity to 125mah per Nitecore product page. I had somehow thought it was 70mah before.