Those are probably the low performing 5200 cells in the KP's. Richard sells them under the EVVA label - protected and button top. Weird - guess low resistance cells do perform better in this light, but the driver raises amps (power) as the cell depletes and produces lower voltage.
Beam shots have been added to post #1 showing the UniqueFire facing off with the Trustfire AK-47 and the SuperNight 12x Cree (LightCastle) POST 1
BLF-SRKDD driver is 46mm, already set up for a momentary switch, and can easily be modded to work with the 12.6v input voltage.
Thanks Comfy, just added it to the list for sure.
SRK-DD (should we take a vote to decide what exactly to call these things?) thread here: https://budgetlightforum.com/t/-/27342
What can be the easiest mod, on this driver HX-1322A2 ??