If you have a 510 battery (same as O-Pen, I have some carts that I got a while back. Was going to try using them with 100% VG but they didn't quite work. They aren't real "high quality" but they will work for a while. Each is 0.5ml I think (or could be 1ml) I can't remember.
They are just like the ones you get in the dispensaries, so they should work. You want them, they're yours.