The Nite-Ize PR upgrade does work in any PR-base light, but the emitter is a little lower than the filament on an incandescent bulb. On most fixed-focus lights, you will be stuck in the flood setting, which isn't very impressive.
For a 2 cell work light I much prefer the SMJLED PR2 drop in bulb to the nite-ize mag LED replacement bulb. The SMJLED is brighter and whiter, with superb battery runtime. The SMJLED is a far superior performer without getting into higher current solutions. Do a search here in the forums for more input. You can buy these here in the "Sell" forum for around $6. I just received 6 more of these beauties from "TrueBlue". Super fast shipping!
I found the NiteIze MagLED bulb to be dim with a bluish tint. I use this bulb in my Dorcy 4 cell dome lanterns/flashlights. I used this on a recent camp outing and was wishing for a few more lumens. I am tempted to re-wire them to 3V so I can use the SMJLED PR2 instead.