roguesoul I know Surefire sort of depends on how much of a drop in voltage you get using 1 cell with the MN01 (E1 lamp). If you use 2 cells in parallel the voltage will be .1v or .2v higher, which will make the light brighter, but probably greatly reduce the life of the lamp. Surefire keeps telling us the MN02 (25 lumen, 2.5 hour) lamp for the E2 is due out this fall. I can't wait for that lamp.