The Coolfire Pebble is an ultra compact device that is even smaller than some tanks. Don't let the size fool you, this device can fire up to 50 watts which may be adjusted to your personal preferences. The Coolfire Pebble features a built-in 1300mAh capacity battery which may be charged via the micro USB port. The Coolfire Pebble features 'Vape while Charging' technology which allows you to vape as you charge your device. The Coolfire Pebble features a spring loaded gold plated 510 contact pin with durable stainless steel threads.