I purchased the first generation eVic. The device is very user friendly, but not extremely durable. After awhile started having some difficulties with the connections, now only certain tanks work properly, like the ProTank, others seem to rather intermediate. They state that is easy to upgrade the micro-code to obtain greater flexibility, its not as simple as it seems, after numerous attempts and conversations with tech support with Joyetech, was able to upgrade from 1.1 to 1.2. Gave up on trying to upgrading to the 1.3 code. If you are rough on devices, which I am, this is not a good choice in my opinion. I have had numerous issues with the head, the button not working at times, locking up and other problems. When it works, it's very good, if you want to keep track of everything you do, number of puffs, etc, then it serves the purpose, Personally, there's just to much to play around with and adjust. With the all the problems I've had with the device, I've moved back to simply mechanical mod with a manual VW adapter with surge protection on the battery, serves the purpose. Push a button and get vapor. Can't speak to the Zmax.