OOZE Smart USB Charger 510 Thread are the best way to charge 510-threaded devices quickly and safely. This little unit prevents your vape pen from over-charging with its auto-shut-off feature. The light on the charger will turn green when your pen is in full charge, and it will prevent sending power from the source so it doesn't get worn out. It is a pocket-sized device you can take everywhere you go. This rapid charging device is specifically made for Ooze batteries and vaporizers. 30 chargers are included.