The 5.0v battery electronicstix sells is rated at 600 mah. For many (most?) people, that roughly translates to between 5 and 7 hours of good
vaping. And, that battery will work in pretty much any
mod that will accept an 18650 battery. You could go with practically any tube
mod that will hold that size batt. There are several less expensive ones and many more expensive ones. I linked to that one just because its price is somewhere in the middle of the road and it is a nice looking mod.