Its been quite a while, but I used to have one of these. Going on memory here, but I think it went red = 3.2V, blue = 3.7V, purple = 4.2V. It won't go past 4.2V, so a 3.2 ohm coil might not be low enough in resistance for it, but that is a matter of taste, really. I don't recall if that unit could turn off for sure, but I don't think it did. Seems that was before that feature became more mainstream. This ego has been recently replaced by the ego-twist, which is a very good unit for the money. Goes up to 4.8V with a rotating knob on the base, and has pocket-friendly 5-click on/off.
One note on your ego. If you are in the habit like I was of removing a drip tip with your teeth, or pulling it off while holding just the batt end, it is fairly easy to pull out the entire insides, breaking the wires and killing the unit. That happened to me with mine. This is always a bit of an issue with ego-type batts, but this unit got a bit of a reputation for this happening.