I have 2 packs of 510 cartos from Nhaler, 1 pack from Vapor Kings and a whole bunch from EastMall. They are all made by DeKang. They all come in the same box. I can't tell which one I am
vaping at any time.
The big difference is end piece. Nhaler, Vapor Kings and a few others have gotten them with the white disk in soft rubber and it is not glued in. You can flick it out easily. EastMall has the white piece glued in. I'm replacing the end with a drip tip or a cut-down 510 cart (cut short enough that the edges don't reach the filler) so I have to remove the white thing and all the glue. I'm dipping the end in microwaved water. Other people have posted that they use a hairdryer or other similar things. It's annoying but EastMall is charging 80 cents per carto. For that, I'll suffer a bit.
ETA: EastMall's sale on them ended. They're not $1 each. Still an incredible bargain.