The OBS Engine II RTA features an isolated rebuildable deck and base which helps reduce the heat delivered from the coil. The hidden side fill design allows you to conveniently refill the tank. The OBS II Engine utilizes a top adjustable airflow valve with an advanced airflow circulation system which helps recycle the airflow throughout the tank. Top Side Fill Dual Coil Design Adjustable Top Airflow 304 Stainless Steel & Glass Construction Made of high-strength 304 stainless steel and resistant glass The top filling design makes you convenient to fill in the tank without detaching other components 510 threading connection 26mm Diameter Brand: OBS Model Engine II RTA Tank capacity 5ml Diameter 26mm Size 56 x 26mm Weight 63g