Fine direct efficient replacement for existing incandescent lamp/bulb in existing torch. Worked well will NiMH rechargeables with very long life per charge and little appreciable dimming. Cool white light. Outlived the two (cheap) torches that I used it in!

I think that the fitting was P13.5S (Single Contact Miniature Flanged Base).

Update 2010-01-11: Thurmond in Texas very kindly sent me an assortment of power LEDs to play with! The very first thing I did was replace the incandescent bulb in my daughter's 2-cell (NiMH rechargeables) torch with one of the pieces Thurmond provided, and it gives a much brighter (and bluer) light and should proably last longer. Even better, those cells were charged in the summer from our PV. The LED bulb itself survived two cheap torches being smashed containing it, by my children's "youthful exuberance"...