I sent 1 of my UDTL's to Jhonutz in Romania a modder on VW to add his NUTZ electronics to it.. I got it back and am very happy with it..Here are the specs.. NUTZ.. 4.2 volt.. --Touch switch --Short circuit protection --underlockout voltage --Boost until the batt is around 3.5V, after that power will start to drop. at 3.2V it`s will shut off as the batt needs to recharge. --RVP protection (revers polarity protection)--if you put the battery in wrong it will not work and electronics are protected. --5 touch on/off switch--good to avoid accidental firing in pocket It works from 1.3 ohm and up to about 2.2 ohm after that you may want more power.. I have tried it with a 1.4 ohm and a 2.0 ohm and it works great.. same vape throughout the battery life.. Here is a picture...