In my Sand MF01S the physical lockout turning the head works properly.
There is no “best”. There are a lot of variations and some work better in certain areas than others. Some give longer runtime, some give higher amps, but there are always pros and cons of each. The 30Q is a good “compromise” battery as it has good amps, good capacity, good availability in button top and a good price.
I doubt this can run flattop batt…
Just received email from BG that 30Q can’t ship to my country after my order placed 4 days ago… Super Sad…
My 5000K Sand arriving any time from now… Sigh…
With this light I believe you can use flat top, but only if you remove the white discs which give polarity protection. So you’ll need to be extra careful installing batteries.
Another option is add a solder blob to a flat top.
A last choice is adding a magnet, but I think it adds resistance and might be risky if the light falls and a magnet causes a short circuit.
BTW, you can add your country to your profile info. Maybe someone can recommend a battery source for you.
Thanks JasonWW for the tips. Will add in my profile. Btw, I’m from Singapore.
Being in Singapore definitely makes it harder to get batteries. Shipping restrictions are getting worse.
I don’t know of a specific company that ships there, but you might try nkon. They are in Europe.
If they don’t shop to Singapore, try this thread. Massive post on where to get lithium-ion batteries everywhere in the world!
You can also search the forum for other people in Singapore and send them a PM to see if they know of a good battery source.
Thats Wrong!
These MFxx Astrolux battery Carryers are all full compatible with flat top batteries.
I have tested it. You do not need to remove the white polary protection disc.
Tested with MF01, MF01S, MF02 and MF04S.
I wouldn’t say it’s wrong. It seems to vary from person to person and from battery to battery. Flat top 30Q did not work on their earlier lights like the MF01. Maybe Astrolux has changed the white disc shape or your using flat top batteries that are not recessed much. Banggood says to use button top, but maybe they are just being cautious? Maybe the white discs just barely allow contact? If so, this might add resistance. The point of the white discs are to prevent contact on the flat, negative side of the battery. If a regular flat top makes contact, are the discs doing their job?
The bottom line is I don’t know if flat tops will work. I do know button top will.
^ I think the problem is that it’s making borderline contact. If the plastic disc is just a tad thicker due to a different batch or manufacturer, or maybe a tad more glue is used to place them on the board, then you may not have contact anymore as the discs will protrude a bit more relative to the metal contact. This is why I think button tops are recommended.
I accidentally bought flat top 30Qs, so I guess I’ll need to learn how to do the solder blob thing - as nervous as I feel about it!
Many thanks for such good news… I have FT 30Q. And it’s much easier to get FT 30Q in Singapore.
Thanks again JasonWW. Will try out FT when the light arrive.
My new purple toy just arrived. Very nice, and a bit bright 
My purple one is apparently out for delivery for the second day, hopefully I’ll get mine today. Unfortunately Yodel are pretty much the worst delivery service that exists in this country!
EDIT 10 minutes later: just received mine too!
Found a chart that showed only 2k Somehwere in this thread, hope it’s higher for at least the 5000k version
Unfortunately I just found out that mine is black and not the purple one that I ordered. 
What do I do now?
They left mine behind the bin….
Hermes did that to me once. I sent a item to someone and they left it “in the porch”… Yh he never found it. Luckily it wasn’t expensive.