You can slip a segment of bicycle inner tube over the central tube. Doesn’t have to be the whole length. Here’s what I did on my FW3A:
It makes a world of difference in grip. I also installed a thick o-ring just below the tail cap bevel. Totally happy with this setup & the aesthetics. No slippage! I recently picked up a Sofirn D03 diving light with very smooth tapered body—did the same thing with it.
SUGGESTION ON FW21 Pro design:
Apply concentric engraved rings along the body, spaced about 2mm. Would help with grip and keep nice aesthetics.
Thicken the head a bit with more aggressive heat sinking. Thermal path from emitter to body needs to be improved for better heat dissipation. This light gets too hot too fast, more so than FW3A. Really alarmed by see a number of reports where emitter domes are compromised after enough hits of turbo.
I got the idea after seeing the NSX4. Didn’t think 4 XHP50.2s would work on a single cell but it looks like they do. It should also have springs bypassed from the factory. Maybe we could call it the “FW21 Pro X” or “FW21 X”. Lume1 driver and USB charging would be great if possible. Could you propose this idea to Lumintop?
I prefer a side switch but it has to always be lit so it’s easy to find. When tailstanding it’s easier to access the button. I also find it easier when operating it with one hand. I don’t like how they extended the FW21 pro and turned it into an X9L without putting much thought into the design. Looks kinda ugly. I prefer a head shape like the one on the right so it’s less noticeable in your pocket…Excuse my bad ms paint drawing skills.