These true Joyetech batteries are universal and fit all eGo and 510 products.

3.3v Rechargeable battery with 900mah capacity will last a very long time between charges.

These batteries have a safety feature that will de-activate the button so that the battery can be stored without accidently being activated. Simply press the battery button 5 times quickly and the battery will be de-activated. Press quickly 5 more times to re-activate it for normal operation.

eGo Battery is not compatible with 510 Charger.  Charger output must be DC 4.2V  420mA