As you probably noticed, E1e/E2e bezel is a two piece design. It is very similar to Maglite bezel design. The lens has been sealed from inside. Actually, if you look REALLY close, you can see and feel(with your nail), the black plastic seal between lens and bezel.
M2 and M3 are one-piece bezels.
p.s. Some E lenses tend to get loose after prolonged carry in your pocket. It takes about a year of normal carry to develop this problem. Pushing on the lens does not help it either. I had two bezels with this problem replaced.
Brand new E2e is fairly waterproof(10-15ft), but looses this future as lens is getting looser.
kev: if you can manage to unscrew the face plate of the E2e/E1e bezel, you'll find that the face plate has the exact same dimensions as the 2AA mini maglite part, and the maglite face plate can be screwed onto the E2e/E1e bezel. the only thing stopping you from using it is the lens; the E2e lens is much thicker than the maglite's lens.