I think I saw 300 lumens on low. There’s a comparison of the highs and lows of the various lights; SRK, BTU Shocker (I think this one had the lowest low at 100 lumens), M6, and some lights floating in a message. I remember seeing it today, but I don’t remember exactly where I saw it. It’s probably in deep down in a thread somewhere — sorry, you’ll have to search for it or someone else can try and find it.
I found it… SupFire M6 - Beamshots (Night pics uploaded)