You can see the placement of the o rings here. The inner one sits near the shoulder to help center the signal tube.
Here is another view
Thanks pennzy, great photo of the o-ring placement in the zeroair review, the CPF post shows 3 O-rings with one down between the tubes like I have one, to center it as I thought…
“If that lower one falls out then it can lead to the tube not meeting the ring on the head concentrically and actually touching the ”live” end on the wall of the head and making the light imposssible to switch off. That happened to me on the 18350 tube I bought from Neal’s and no matter how I tried I could not get that lower O-ring to go back into place so I ended up shrinking some battery wrap around the tube which worked perfectly to keep it centred inside the wall of the light”
Good idea about the shrink wrap too.
Figure I'd share this exchange with Lumintop a few weeks ago if this hasn't already been settled or for those that missed that:
Doesn’t sound right. For a “small batch”?. Maybe someone can verify this. I’ve gradually lost respect for Lumintop as a company over the last couple of years, but I did want another FW3A if I could get one identical to the originals.
Based on my experience with Lumintop I’m kind of surprised they even answered your question. Thanks for sharing that.
I’ll believe it when I see it. Thanks for sharing
Has the HL3A been downgraded similarly or is it still a good headlamp?
Get a Fireflies PL47G2 instead, more flexible emitter options too.
They are on sale right now, too!
If only I weren’t avoiding the migration to 21700…
Bit of a late reply, but yes the HL3A has also been downgraded. I bought one a few months ago and it has the FET+1 driver. I really wish the Lume1 drivers had the ability to be used in the HL3A and EDC18, let alone be available to buy anymore!
Thanks for saving me the hassle of finding out for myself. Taking the HL3A (and any Lumintop product) off my shortlist.
it would be better if they just stopped produce the lights instead they downgraded them so badly… now they just make the lights look terrible vs how the orginal is… 
Money…
True.
I have FW3A from 1st batch without any engraving. That’s a keeper.
Mike
I wonder if they degraded everything, including the Titanium and Copper/Brass versions. I would be super pissed if I spent 100 bucks on a Ti version and got the degraded driver and crappy optic.
Lumintop are shooting themselves in the foot because I have no confidence to buy ANY Lumintop product. If they want to change the specs of product for the worse they need to use a new SKU and product name so everyone knows it is different.
Have to agree, downgrading existing products makes me extremely reluctant to buy any of their new products. If only there was a good FW1A alternative (i.e. Anduril, Tail Switch, Head Diameter <28mm).
From what I’ve heard, it got downgraded again to be a FET-only driver. So I added another warning in the OP.
metoo, the first fw3a is best 
hope it never dies haha.
wow so how terrible is the current batch ??
From the first post.