I had 1.5s in but for some reason they are now reading as 1.8. They don't last at all. Had mine two days and coil is going already. Not best pleased. Love the look of the tank, makes my setup even smaller profile and I enjoyed being able to fire my Vapes a bit higher bit not happy with how quick the coils are burning out. They aren't cheap either. Flavour is stronger at 12w on the nautilus mini than 18w on the x. Flavour gets better for certain liquids at 20 to 22 but the coils go so quickly. I like the air flow better though on the x, much smoother and get less of a heavy throat hit than on the mini.
Got a Delta 2 and rba deck coming this week though so probably won't be on the x for long apart from when I need a really sneaky vape.