I use in rotation a pico,coolfire 4,coolfire 18650 and 2 provaris,lol. I do like the idea of safe,thats why im skiddish about upping my wattage. Using the subtank mini with RBA all the time. I prefer MTL. I have upped it to 15 watts on this 1.4 coil and it is better but will also keep trying new things too. I had no idea i would end up chasing a cloud when i started..