Hey..
It should be. 4.2v / 420mA is what were after. But some
batteries/chargers have reverse polarity. So you need to be careful of that. That would almost definitely cause a failure.
Chargers guaranteed to work are the Joye EGO/510 chargers,
smok Tech Ego/Riva chargers, EM Riva chargers, and T-Rex/Firefly Chargers.
Ty