Hi Random! The V4L cartomizers do not fit the 510 connectors (Joye Ego). I use both. I love V4L's pre-filled cartos, so I bought a couple of their
batteries to use. For the Ego, I buy blank carts from another vendor and fill them with e-
juice. It's good, but when I'm busy, I use V4L. I believe the V4L is model KR808D - someone will correct me if I'm wrong. I've been happy with the flavor of all their premium cartos.
Liberty Flights sells connectors so you can use the V4L type cartomizers on a 510 - but I don't know how they work yet since I'm still waiting for mine to come in the mail.