Mr. Maukka, thank you for very detail review with lot of information!
Do you think e21a is your favourite led? How does it compare with sst20 95cri?
The kr4 driver looks different from normal driver, do you know if it is similar to loneoceans gxf22 driver? GXF22 - Very Low Resistance FET & Constant Current Driver with Fuzzy Logic + Microphone I don’t think I saw it in any other flashlight yet. It will be nice for kr4 to have fet mode as well, but maybe not for e21 version.