EDIT: I read SMOK PRIV V8 from OP, so it has a removable tank. But still... don't buy it! Read along...
Funny, I own one... If I were you just don't get it. It comes with two coils, 0.25ohms pre fitted and 0.15 ohms as an extra. That 0.15 coil is useless as this is unregulated mod, it fires up at 60 watts when fully charged and burns that 0.15 coil in about 1.5 seconds. Not burn the coil but burn the cotton and you're stuck with burnt taste forever in that coil. You can use the 0.25 coil for like 2 weeks if you are a moderate vaper and you will need a new one after that.
The battery cover will worn out quicker than the coils and will make loose connections to the battery. I already soldered what's supposed to be a pin connection because I guess the pin got hot and melt the plastic housing that made itself sink in it's own hole. The only reason for you to buy it is if you fancy repairing broken electronics. The Priv V8 will be your next project in less than a month.
For the exact same price.. I recommend OBS cube. You can choose to buy the mod only or with a sub ohm tank, but the tank is similar to any replaceable coil tanks. So I suggest you just buy the mod only and use the saved money to buy a proper RTA. It has a built in 3000mah battery that is enough IMO for any single coil RTA. It's built in so you don't need to fiddle with anything. I only recommended it just because it is identical in pricing, at least from where I bought them.
If you can spend more, you need to look elsewhere and forget the SMOK brand.