It will probably work with a S1 / S41 18650 tube.
The threaded sections of the A6 tubes are shorter (and smaller in outer diameter).
Had a chance to power up my S42 XPG3 last night. My observations:
The UI is horrible. One of the worst I’ve ever seen for an e-switch light. The UI is as follows:
- Group 1: 4 modes: short click to turn on and then short clicks to cycle modes. The light remembers the last mode that was used. Long click from any mode to turn off.
- Group 2: 7 modes: always starts in moonlight with no memory. Short click to advance modes. Long click from moonlight shortcuts to turbo. Long click from any other mode turns the light off.
- Double-click while the light is on to switch mode groups.
The problems with this UI:
- Long-click for off is inconvient.
- Can’t access moonlight or turbo in mode group 1.
- Can’t turn the light off from moonlight without first switching to a brighter mode.
- No shortcut to turbo from off.
- Very easy to accidentally switch to the other mode group.
The E14II’s UI isn’t perfect, but it’s still much superior to the S42’s.
Other observations:
- Battery tube is too short for 18350. I knew this was going to be a problem though so didn’t try to force it. Instead I swapped in my S41’s 18650 tube which worked fine out-of-the box with no modification and no forcing of the battery.
- The screw threads for the hammer at the bottom of the light add unnecessary length. With the 18650 tube installed the S42 is the same length as the Manker E14II, when Astrolux could have easily made theirs a much shorter light.
- The light feels very lightweight and much more pocket EDC friendly because of it compared to the E14II.
- The battery cover is too loose. The socket for it in the head and/or the cover should be redesigned to give a much firmer fit.
- Very nice cool white tint. Slightly better than the cool-white tint on my XPG3 E14II
- Max turbo output on the S42 is noticeably dimmer than the turbo output on the E14II. The S42’s head also takes much longer to heat up than the E14II. That’s a good thing considering the E14II heats up to uncomfortable temperatures in 10 seconds or so. As the previous poster noted, turbo output in the S42 dims gradually over 30 seconds or so. I suspect the driver is programmed to do this intentionally to prevent the light from overheating.
- The button feels nice, but protrudes well above the head. The more flush E14II’s button might be less likely to accidentally turn on in the pocket.
- USB charging seems to work fine.
What I like about the S42:
- Anodizing and workmanship appear excellent
- Light weight makes the light practical for EDC carry even with 18650 tube installed.
- Quad emitters with good tint.
- Low price… less than half the cost of the E14II.
+1 on turning the A6 tube around - that's what I did, but might have still added the washer in the tailcap, not sure - probably noted from yesterday in my posts.
djozz - hhmm, still at work, but think you are right - alum is thinner perhaps than the copper of the S41. Never was able to get the bezel off my S41 though.
The interface is awful, my daughter does not know to turn it on, and the batteries, not the ass loads, the usb top, is the easiest to fix
Put mine back in the box waiting solution from @banggood
EDIT: Oh but they did finally refund my points from the cancelled tube order 
I have the same, and I think the same, perfect review, you have tried to load it? With a samsung 30Q, do not load it until the end, it tastes bad, because I like it a lot, and since it lowers a lot of intensity, Runtime
Yes, I’m running mine on a flat-top Samsung 30Q. Light runs perfectly.
Yes, but from the usb of the flashlight, it is not able to load it at 100%.
Reversed the A6 tube - still no contact. Checking internal and external screw dimensions I can see now why you did that and added some washer; that is right, A6 tube is a little bit too short at least at one side to make contact, so will retry once I have found a rightly sized washer. Thanks for explanations that clarified the issue. Apart from that, the rubber hiding the usb charging plug keeps going away, it's clearly too loose to stay in place - BG is supposed to provide replacement, correct?
Ohh - after you reversed the tube, please check if the driver side contact works by grounding the Batt- end to the housing, tailcap off of course 
. It should work, then least you know the driver end has good contact.
Ah. I haven’t tested the charger to see what it stops at. It’s not a good sign if it’s not fully charging.
i got it yesterday and try it with this meco 16340 batteries it worked for a test but this light in my opinion is a total failure.
the UI cant be turned on and off with 2 clicks no its one click for on another click to go to the next level and a long click to turn it off this makes in unusable for any random person who picks up this light.
the next disappointing point is the strobe its so weak and soft you can look into it straight away without feeling disturbed (i don’t know who made this but strobe is around long time and easy to reproduce from existing proven lights)
next ridiculous Mode is the bike flasher its 3 seconds on then dark for a 1/10 of a sec then one for 1/10 this repeats 3 times i never saw a worse biker flasher ever. here again just take a sample from the blf a6 light this modes are all perfect why fail after doing it right ??
the user manual medium grey on white in the smallest fonts available on earth someone explain that???
this is just the UI all the hardware stuff are discussed here well already
and after playing with it for a less then an hour its stopped working at all now its total Dark
paypal dispute time,
So would it be possible to make a fixed BLF version, as I wrote here Anyone for a Astrolux S42 BLF Edition? ?
Banggood had to change Usb cover, Tube and we need a good UI
Joe
I don’t think this is necessarily true. Although I did remove the spring and install a solder blob, it was only barely enough to make the cell fit. It would be much better to have another 3-4mm of tube length to accommodate the various length of cells.
I would rather them fix the one I already have. I don’t want to pay then again to get what I should have gotten.
i wonder why they didn’t copy the usb port solution from manker this rubber thing makes this flashlight not waterproof at all because this comes lose so easy…
its funny someone copy a product and instead of improve it and make it better they made everything possible worse
Ok, definitely crushed the cell a bit, opened a ticket with banggood, lets see what they say.
I was stupid to assume this is a S41 with charging…
The driver spring is the main problem.
But it’s not the only problem.
The tail spring is too tall and rather stiff.
it should be replaced by a shorter one or made shorter by cutting off a coil or two.
Why would that be better?
You’re not gonna use protected cells in this light anyway, because it’s a high current light.
That UI sounds ridiculously bad. What the hell were they thinking?
Something makes me think that if somebody from Banggood/Mateminco/Manker/etc… came to one of the resident firmware experts like ToyKeeper or Tom E and said “We’re making an e-switch 219C FET quad, will you write a firmware for it?”, the answer would have been yes and the result would have been awesome.
On the other hand, credit for being the first light on the market with a 5000K, 90 CRI 219C.