The BTFC RDA is 25mm in diameter, providing a spacious deck for easy building. The BTFC RDA features adjustable double airflow system - top airflow and bottom airflow. The dual-post deck is very easy to install coils. The four air holes on the build deck brings direct airflow underneath the coil to maximize flavor. The AUGVAPE BTFC RDA is switchable between 810 Delrin drip tip and 510 drip tip with an included adapter. The pack also comes with a BF pin for squonker MODs.