Went through 2 packs with each coil lasting under a week, barely any vapor after the first 2 days due to gunking. Of course thats just my personal experience, but I honestly would just recommend buying some wire and making your own. When I started doing that, I finally saw what they hype was about. Amazing flavor and vapor, with no burnt taste at all. I dont think I can go back to using a tank again, as I doubt I could fit my coils on an rba deck.