These are really hard to find. I did manage to get my hands on two from LJ's E Smokes in Edgewater, FL, but I cleared out their stock. I also have the ego style USB mini VV. The mini works ok as a VV, but it is featureless. It only has one button which is used to raise and lower the voltage with rapid depression of the button, and it has no display of any kind. I use only RBA tanks, and the mini is so small that the RBA's dwarf the unit. This other one is a keeper! It's big enough to comfortably hold my RBA tanks comfortably. I wish it had a resistance measurement, but otherwise a great unit as a pass through. This one also uses Li Po batteries which is a big safety feature. I have had standard ego's fail big time on me. One more thing: spend $10 or so on a 2 amp usb charger. The idea of schlepping another something may be anathema to the road warriors, but risk of damaging a pc is just too great.