They’re all Maha.
The old white cased, non LSD Powerex version had a 230mAh rating. That was the only one available until about a year ago or so AFAIK.
The new back cased LSD Imedion version has the same 230mAh rating, but is LSD. I was mistaken in thinking the capacity had been increased, it stayed the same.
I had forgotten that at the same time the new Imedion version was released, they upgraded the non LSD Powerex capacity from 230 to 300 mAh. Apologies for the confusion. I didn't check the photo I linked closely enough to see if it shows the old or new Powerex which look identical except for that number. But regardless, for faninor's battery box application, the Imedion version will probably last longer than the slightly higher capacity new Powerex, simply because the current drain if the battery box is likely so low that self-discharge would probably drain the battery before the mics do. IME, the Powerex ones will self-discharge to 7-8V in about a week or two. The Imedions retain over 10Vs of charge for at least a month, which is as long as I've gone between use with them.
I chose the Imedions for that reason even though my current drain is higher, and they've been working great. I suspect they may have a longer life too. I got about a year, maybe a year and a half of heavy use out of the old Powerex ones before they went wonky and died.. and their death was a bit of a mystery problem at the time which is why I mentioned the best practice for checking them under load before and after use to catch their eventual decline before they cause a problem.