AquaLung Dimension i3 Back Inflation BCD By placing the air cell behind them, the diver is more streamlined The integrated i3 control system provides a single touch control for both inflation and deflation Flat e-valves are very streamlined and effective. One-way design keeps water out The multiple dump feature means that when you depress the i3 lever, all of the flat e-valves open at once! No more reaching for the wrong valve Custom backpack is thin to keep cylinder close to your center of gravity and efficiently distributes the cylinder weight