Mostly, but that and the narrow head help to really light up translucent stones and also fit into places where a larger head can’t (all in the name of really limiting the focus spot). Like how your hand looks when you press a light up against it vs. having that light 1/8” above the skin. I bet if you youtube jade inspection there are probably oodles of videos. UV lights are also popular here. I’m not into this myself but read a little about it some years back. Apparently there are different types and grades of jade, as you’d expect, but also a hot market for fakes and resins passed off (and priced like) real jade. Finished goods, but also rocks and nodes and whole boulders (for the people that make them into products). I think it’d be neat to live where jade or other exotic stones could be found…there is the occasional geode or bold quartz crystal around here, though. 
So, does anyone know how to actually replace the spring on the M21X series of lights?
It looks to be a special spring design instead of being on a PCB, so it looks like my plan for replacing it with dual BeCu springs will be a bit harder than expected 
From what I’ve noticed, he’s used a variety in the series depending on host (and sometimes with the same host). If you mean the triangular-base spring, it’s held in place with or without a retaining ring. Use a pick or angled hook to pull inward on the open leg of the spring, pull it on out. With a retaining ring on the lights I have, the spring sits in there pretty loosely. Without the ring, the pressure fit is very light (battery pressure when assembled provides better contact). I’d make your springs considerably longer (at least for the lights with heavier 26650/26800 cells and probably 21700 too)…longer than stock, after accounting for compression stack loss. The stock springs do the job but could stand to be both longer and stiffer so bumping/dropping/tailstanding the lights doesn’t cause the cell to lose contact with the unsprung brass contact post on the driver (mode changes or turn-off when that happens).
The Chinese market is very different from the international market. Although China has a large population, China’s basic lighting facilities are relatively complete. Not many people need a flashlight.
Chinese consumers are accustomed to direct communication with merchants. Emails and forums are not popular here. Consumers hope that any questions can be answered within a minute.
There used to be a Chinese flashlight forum, but it’s now in an abandoned state. At present, the largest community discussing flashlights is Baidu Tieba.
Most Chinese people only care about the brightness of the flashlight, and do not have in-depth research on other parameters. For example, most people do not understand the parameter of color rendering index. Many people don’t know that the unit of brightness is lumens. If the user wants to know how bright the flashlight is, he will ask what the power of the flashlight is instead of the lumen value.
The Chinese flashlight market is riddled with false propaganda, Maybe you can often see some flashlights have a range of 10,000 meters, but the price is only about a dollar.And larger flashlight companies will put more money into propaganda and marketing than R&D.
That’s part of the reason I can think of.
I understand the Chinese market, but I am not willing to cater to the Chinese market to engage in false propaganda, and I am not willing to participate in price wars.
My warehouse only has the flashlight host, driver and LED. I organize the daily orders and deliver them to the workers to assemble the flashlights.
But even so, it still requires a lot of money to prop up inventories.
for example ,recently, I ordered Nichia 519A 5700K 5000K 4500K 4000K 3500K 3000K, a total of about 21000 LEDs, to meet the needs of flashlight enthusiasts.
You beautiful man.
21000 LEDs!!!
That seems like a massive amount of money holy crap.
Between BLF and r/flashlight we’ll buy them all.
You took the words out of my mouth :partying_face:
@corellux, I see.
At least the M21F has a retaining ring, which means I could probably just stack appropriately sized copper sheets with my dual springs soldered on them, which should work quite well then.
Based
I’ve seen this word used a few times recently. I have to ask, what does this mean? Sounds like some sort of slang. I grew up in the 80s, so I’m assuming it means more or less the same as ‘word up’ back then.
“A word used when you agree with something; or when you want to recognize someone for being themselves, i.e. courageous and unique or not caring what others think. Especially common in online political slang.” - Urban Dictionary
Ah that makes sense. Thanks. I tend to stay away from online forums these days (I’d rather stick my head in a wasps nest, BLF being the exception), so there are probably a few more expressions that went under the radar.
Hi Simon, I see that you are now carrying M3-C with a 26800 extension and battery. Do you have any plans to sell L6/L7 with 26800 extensions & batteries in the box?
Noooo i bought the m3-c and the extension separately like 3 days ago :cry: already have 5 cells but i never say no to an extra 26800 :nerd_face:
Thanks for the explanation! I always read about light pollution in China. It’s so freaking bright and night is like day with the excessive lighting there, it doesn’t allow much opportunity for anyone there to “play” with flashlights. I also notice most Chinese flashlight manufacturers only like CW and ignore high CRI. I guess light quality is not a “concern” yet for a developing country as there are far more important things their citizens need to worry about. The flashlight hobby and pursue for light perfection is such a First World hobby.
4x18a is the best sbt90.2 flashlight at the moment. Simon is a super star , I love my flashlight and I love you Simon !
Ackchyually the best sbt90.2 light is 3X21A since it have 10% more capacity :nerd_face:
@simon, do you think it would be possible to replace the 5000mah 21700 cell for the Lishen 4500mAh cell for GT FC40 lights?
At full power, the Lishen 4500mAh 21700 actually gets better capacity than corresponding 5000mAh cells.