they are 2 watt 25ohm rheostats, when operating a the high end they almost burn , but i figgered that the TOTAL power going to both the leds and the rehostat dont mean that it is all going to the rheostat.
because i am a learn while i burn, kinda experimenter, they seemed to work.
One of them is on the Amber spot led (luxeon) and it is already at 25ohmes +- a bit here and there, to run on the 12v
so it is on a 100ohm pot probably a 1w.
the 25s are radioshacks finest 2 watt i think
and they dont ever go to 0ohmes so the switches can jump past the pot for full power.
they are quite large items, dont know if they would fit in the base of a mag, about 1 1/4" in diameter
but they did work much better than expected, and even though they are disipating heat, the whole circuit current drops lots when turned down.
my guess is the last 2 wires on 2 of them are getting very very hot.