https://www.dealextreme.com/details.dx/sku.50946

There are 3 other models with slightly different bodies/features for $5 more:
https://www.dealextreme.com/search.dx/search.YJ-E02. The last one has a solid switch boot and hardly any normal heat fins. Actually there are only 3 - the E02 model is just listed 2ce with 2 different prices.

Maybe in a while they'll have just the battery holder and pouch as an accessory. I'm glad the light has a fast strobe - that is so hard to find on a Chinese light.

Battery not included...

That battery pack looks interesting but yet scary at the same time.

Interesting because it allow the user to use their own pick of cell but I wonder does the pack has a built in protective circuit board or do the user have to use protective cell. The scary part is that this potential can be bad depending on the knowledge of the user. If the user uses the wrong cell such unprotective cell in that holder which may not have a PCB, then that can be risky. Also it still does not solve the problem with balancing cell if the user are not fully aware of what to look for when it comes to multiple cells.

There is no need for a PCB on that if you use it as intended. The user is supposed to open the can and charge the cells in a cell charger (or two) -- there is no pack charger included. If your cell charger has independent channels it will keep them balanced or at least fully charged. There is no more danger than charging 18650s for your flashlights, but you would want to use protected cells.

It could get scary if someone tried to hook a pack charger up to the battery holder/dumb pack, but they make it difficult to to this by accident. If you look at the pics (and if they are accurate): typically the male connector is on the lighthead - they put it on the pack. To use a pack charger someone would first have to make an adapter. Someone with enough smarts to do that may wonder WHY they need to do that. In that case, yea you'd want a PCB (or a low deductible).

Advantages to a dumb pack are that it costs as little as $20 to replace the cells and it is very easy to monitor cell health. Being all enclosed as it is, it is a very nifty holder for a dumb pack.

The one pic of the open pack looks like the end screws on like a lid AND has 2 screws thru the lid into the housing. It would be tedious to undo those for every charge. EDIT: No, those are just alignment pins sticking up from the floor so you dont insert the cells rotated 45*.

BTW, that holder looks like it is 4P so you couldn't just change the cable and use it on a MS. The description(s) say the light is 3.6-7.2V which I assumed would be 2S2P. It might just be wrong or a) the lights run at 3.6V rather dimly for a long time or b) they are doing something to boost the power to 7.2V. I cant see how the carrier could be wired for 2S2P/7.2V since the alignment pins allow it to close more than one way.

Also, the other lights are not just a different design/color but the pics show some with a 50+mm face, one is also an MC-E and the others P7.

I assume more like a). They must be driving the LED at the Vf of 3.6v. It listed at 7.2v max which is below the 7.4 nominal volt of a 2S. If this is true, then the 4P will keep the pack above the 3.6v for a while before dimming start.

I still like the pack even if it is 4P. I got two single cell flashlight which would be ideal to use that pack as an external pack. It can double my run time but then it will be one expensive holder and what will I do with the light head?

A Luminous holder would work for the flashlight. They come with battery contacts that you can wire them however you need them in about 15 mins. Cheaper for certain.

This battery was mentioned on another forum. The company selling it claims to have hand-built them in house. They also claim it has the same capacity, is the same size, and uses the same connector as the original MS battery. At $40 it certainly seems like another viable option...

If you poke around at the Ballistic site, you'll also find a 5200mah MS pack for $49, and a 7800mah pack for $80. You can add a charger for $15. The 5200 looks like a bargain (about the same cost as the Gemini) as long as there is no HazMat fee. Seems easy to like a battery from a US RC source.

Almost like a cottage industry popping up with MS battery solutions.

I just bought a Tenergy 8 cell battery and soldered on my own MagicShine connector, cut off of an extension cord bought from DX for $3. I have a lot of run time.
At the time the Tenergy 8 cell packs were on sale for < $30, but I think they're about twice that now.