After my wife won an M4 at the Surefire party I have been playing around with it. It is awesome on the low output LA, MN60. Pulls about 1.45 amps, much lower amperage than MN16. It will take a longer body to run it with three 17500's, better to have three 18500's, or an even longer body with three 18650's, but the beam is beautiful, oval, but beautiful. Bulb is frosted.
Bill