I got the 510 mega also sold as 520 and I go for hours! No complaints, very consistant vapor, it only slows up when it is almost ready for a charge, I run it all the way down to make sure the
batteries memory is for the full charge every time. 510 is the battery, the carts and atomizers are made to fit it thus the 510 label. They do fit the blue too oddly, and I tried the reg. 510 atomizer with a Blu Battery and there is a world of difference, lots more vapor. Of course the Blu dies after about 1/2 hour but at least I have something to give my security HA. I don't
vape at work so 1 mega lasts me all day and up to about 10 pm. I go through
juice like a fiend so I may be a really heavy vaporer.