A Kayfun rba simply rocks my vape world. Most any build will work on it, where it really kicks azz, is with a micro coil build, vertical mounted serial duals, or a SS mesh cotton core hybrid build, crank it up to 14-19 watts, and you got yourself a Mount Saint Helens Event.!! Even a single micro, horizontal or vertical, rocks solid juicy vape. Kayfun or the Russian great rba's for both a variable device and a mech mod. Works great on the Provari, but looks so much better on my Nemesis clone mech, and vapes better too, since the P tops out at 15 watts, the mech is only limited by the ohms of my build. Currently have a .9 ohm build so hitting about 19-16 watts, depending on the voltage that my battery is at. Slap the kick in and then we are maxed at 15 watts and don't have to worry as much about the ohm's of my build.