Just got an order of 10 of these in the mail today. Got 'em from nHaler.com mainly because I like how 'hard assed" that vendor is, he says he won't sell something that doesn't work well, like the G4s or the 510 G5s. I filled the first one with Johnson Creek Tennesee Cured and it leaked a tiny bit a the beginning but stopped - less than a drop of juice leaked. The first two hits where not very good but the third was BADASS. After a few hours of using that, I opened another G5 carto and filled it with some Coffee from Ms. T's (always thinking Mr. T -pitty the fool - when I type her name) Bakery and it didn't leak any. Vaped on both for a while longer and my TC was getting low so I put some more in the carto. I must've put too much in 'cuz it came out - A BUNCH. But alot stayed in and it's working fine now. So though I'm not a connosieur of cartos, I recommend the G5 clearomiser. You just have to be careful with 'em.