I want to buy one 21700 FW3A
Its available on banggood also i see.
It’s everywhere but here!
Received mine a few days ago and am trying to solve a problem. Light illuminates after battery is installed and screwed together and with the head and tailcap removed I’m reading a short between the contact points of the inner switch + tube and the outer tube - contact points.
You could wrap some Kapton tape around both ends to insulate and see if it helps…
Mine was bought in BG (11.11) https://budgetlightforum.com/t/-/31589/4838
I still haven’t bought anything from Neal.
Shipping fees ($6 each order) kill the deal and… Neal’s reputation is not the best…
the mails have been sent November 24th
The Lumintop FW21 available to order from nealsgadgets.com!
please note!
This one will fit the battery 71mm 21700 (shorter tube than 1st batch!)
Lumintop changed the design to make sure contact is good and to avoid the use of protected cells! (customers complained about tripped battery fuses)
use my COUPON CODE: NDFW21 to get 30% OFF ( $39.16 )
please use this LINK to visit the shop for additional information and to order!
I heard one person report that the Vapcell 4500mah was 72mm long.
Martin says the light can accept up to a 71mm cell. So it doesn’t look like that battery will fit.
So when you screw the light together it automatically ramps up?
After installing battery and screwing on the head it ramps up, after which sometimes intensity varies up and down, and switch has no effect. Meter reads 0.00 ohms between inner switch + tube and outer body tube - with and without the tailcap.
Oh, so just the battery tube and the inner tube, no head or tail, you measure a short? I dont think I’ve heard of anyone having this issue. (Except Toykeeper on her prototype)
Do you see any of the black anodization rubbed away or scraped? It seems the fix would be to wrap the outside of the black tube with kapton tape like Kawiboy said.
I didn’t see any obvious damage to the anodizing. I plan to try kapton tape but I have to order some. Before that I’ll try wrapping some teflon tape around the inner tube.
Look for a fragment of metal stuck between the tubes or stuck into the anodization layer exposing the aluminum.
It only takes a whisker of anything conductive to cause a false signal.
Fixed! Seems to be operating properly now. 
Quick clean of inner tube and inside of outer tube, inserted inner tube to a point with o-ring seated and very high resistance (55 M ohms) between the tubes, installed the tail cap, and inner + tube to outer reads open on the 60M range.
Even so, I’ll add kapton when I get it.
thanks thats a bummer… should have made the light 2 mm more to give room for even longest batteries imo 
At this point I am very satisfied with the fw21. The only suggestion I have is a groove at the inner edge of the head end of the outer ground tube for an o-ring to help maintain no-contact space between the outer body ground tube and inner tailswitch + tube. Anodizing may be good for insulation but it’s not perfect.
What size trits fit in the slots?
1.5x6mm trits
Just reviewing the FW21 for my channel now, complete fail of a light (Lumintop recommend 10A> unprotected button tops, none fit lol) and Lumintop won’t answer my messages which furthers the misery of this project.
where did you get it?
the first batch had a top long tube
Banggood.