Yes. Just like the 2019 or 2012 version…. you can turn the control ring and get a gradual smooth dimming all the way until you can barely see the emitter is lit when staring directly into it from close range.
Appears to do nothing as far as I can tell. The RRT01 has the hole in the ring but the RRT03 does not.
Yes, the 2019 head fits and works with the 2020 body tube.
Protected 18350 are to long for the rrt-01 2019 version. Do they fit in 2020 version?
Thanks Firelight, means the weak spot of the 2019 model, its paper thin tube, can be fixed!
I don’t have any protected 18350, but they should have no trouble fitting.
The 18350 that the new 2020 RRT-01 and –03 comes with, includes a built-in USB port and charging circuit. It’s much longer than my Aspire 1100 mAh 18350 and is probably longer than any protected 18350 cell.
The overall light is pretty big for an 18350 light. Especially so for the RRT-01 which is slightly longer than the RRT-03 due to the longer reflector. In 18350 configuration the new RRT-01 is about the same size as an FW3A with 18650 tube.
Is there anywhere we can purchase the new 18650 extension tube?
Do AA cells rattle around in there or do they provide an adapter?
Nealsgadgets
My first-gen RRT01 will run on AA/NiMh voltage, however I don’t have any body tube that supports that size cell. Maybe one can be adapted from another Jetbeam light.
Firelight2
Can we ask for some pictures, please? I would like to see rrt03 and rrt01 optic.
I think you would need to buy the two extenders from one of the vendors, there is no actual 18650 tube
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there is no Low Voltage Shutoff in the RRT-01 driver, and no thermal step down
a responsible user can manage unprotected cells, by observing when output gets dim, or starts to flicker, and/or by checking voltage manually. But if Granni falls asleep with the light on, it IS possible to overdischarge. So give Granni eneloops 
It is also possible to damage an RRT-01 by tailstanding it on maximum, using LiIon. So, dont tailstand on maximum, as there is no thermal protection.
this is what my original 2012 RRT-01 does when voltage goes below 2.5v (by which time max output is less than 15 lumens):
I wonder who will be first to test the 2020 maximum output with AA Eneloop?
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review says 18350 protected does work in the 2019 model…
(vinh also reported that protected 18350 works in the 2019 RRT-01):
Thank you for this valuable info! I had no idea that the RRT03 would lack infinitely variable control. Only 3 steps and the lowest isn’t moonlight? That’s a deal breaker for me. I can’t see what use there would be with this light, as it’s primarily a task light (RRT-01 has been that, due to infinite variable). Might as well get an Emisar D4SV2, as it implements the aux LED’s much better.
I meant that with protected 18350 2019 version cannot be assembled without small gap.
Thanks! 
In my RRT01 2019 with protected keeppower P1835C2 the gap is about 0,4 - 0,5mm
Edit.
My light has this gap even without battery
Protected 1200mAh Keepower 18350 in 2019 RRT-01 does not close all the way, but it does work and does cover the O ring…:
I can understand how some people would not be happy about that gap though…
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Listen to the Vinh Salesman Spin:
the exposed Brass gives a “very nice cool look” 
Wow. This gap is HUGE. Now I think I’m lucky my KP fits (almost) perfectly.
My 18350 INR KP 1200 mAh fits perfectly. No gap.
maybe measure your protected 18350 battery, and the brass gap when installed, so we have some specifics to compare
fwiw, the Protected Keepower 1200mAh 18350 is supposedly 39mm long (on left)
can you confirm that length?
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the UNprotected is shorter (pictured above on right)
I have the UnProtected Keepower 1200mAh 18350, it is 34.7mm long… a difference of 4.3mm shorter, without the protection circuit.
[quote=jon_slider]
I can understand how some people would not be happy about that gap quote]
Yikes, I wouldn’t want to test it’s water resistance with that gap.
the O ring is still covered… no change in water resistance
the gap does not affect the function of the light, it is a cosmetic issue only