I have two bottles of liquid that I use. They are 16mg and 18 mg. To me they seem about the same and I don't overdose at all even when chain vaping. The strange thing is that where I get my stuff (kiosk at local mall) the highest that they sell is 18mg. I hear of so many people useing 24-36. I didn't even know you could get that high, but I doubt I would want higher than 18mg anyway.

