Uwell Crown 4 Tank The UWELL Crown 4 IV is the ultimate flagship vape tank structure, introducing a new line of Crown coils with materials improvements, a simplified threaded top-fill system with 6mL maximum capacity, and a striking visual design. The Uwell Crown 4 presents a brand new patented self-cleaning technology within the atomizer core of the new Crown line of coils, absorbing excess eJuice into a condensation holder for later vaporization during usage. This helps reduce on wasted eJuice and lessens the need to clean the detachable structure of the tank. In addition, within the atomizers is the patented Pro Flavor Core Optimization System, or Pro-FOCS for short. This system recycles the in-taken air twice through the core of the atomizer to saturate the recycled draw with additional flavor from the vaporized eJuice. Also, the Crown IV Tank hosts a simplified quarter-turn threaded top fill system for faster refills and less downtime between cloud chucking sessions. Furthermore, the Crown 4 has a visually striking design, being hand-polished and knurled at the top and bottom ends, making airflow manipulation and unscrewing of the top fill system even easier.