HotVapes offers two 510 usb chargers as well as wall and car chargers.  In order to use the wall and/or car chargers you will need a usb charger: it plugs into the wall and car chargers' usb inputs.  This is actually a convenience and helps keep charger costs low.  Of course a usb charger may be simply plugged into your computer as well.

Either usb charger is compatible with any 510-threaded battery; the corded charger is recommeded for Torpedo batteries.