I've used the bulb from my Cool Blue in a number of other lights. If you use it in anything less than 4 cells, your output will be noticeably diminished. The only light I've tried it in that it just won't seem to work in is a Docter Aspherilux 125. Right now it's found a home in my Energizer Arc White...coupled with the Arc White's CCFT, it makes for a very nice, long burning emergency light. There are brighter Pr based LED's out there, but the one from the Cool Blue serves it's purpose.
PJD