This little device is the worst piece of crap I've ever bought. First, (and probably my fault for not actually researching it) I thought the tank was a "tank." It's not. You have to wedge the glass piece between the top piece holding the coil, into the base piece (where the vent is) and squeeze as hard as you can and pray the threads catch. It took me several attempts and a whole bunch of cursing.
Then, the "tank" area holds enough juice for... 10 min. of vaping? And for the first day the juice was just pouring out through the vent hole, even though I didn't fill it all the way. I have been vaping 15 years, I know how to prime coils and to leave some room when filling a device.
I basically set fire to $20. DO NOT BUY THIS P.O.S.!