These adapters work very well. I was using a 510-4081 adapter on my eGo for a while to allow me to use my Safe Cig (4081) cartos on it. No probs. I actually need to pick up a 4081-510 adapter now, since I've decided to switch totally to 510 cartos, so thanks for the link.If anyone else needs a RN4081 battery to 510 cart adapter here is a link. Thanks again for all the help!