The MV VV mods are excellent, I have two of them. The tanks and most anything else you may want to try will work very well on them. If you're thinking of getting one I strongly suggest you get their latest release, the built in volt meter makes it a lot nicer to set the voltage. Variable Volt Box Mod w/ Voltage Indicator
Errol
Wow, very cool! I see it has a 'regulator' in it, obviously to regulate the voltage, but does it maintain voltage across the life of the batteries? In other words, if you set it to 3.9 volts, will it stay there until the batteries are pretty much dead?