The X650 is the featured performer in the SCUBAPRO all-star line. This unique second stage incorporates an exclusive valve design that results in unparalleled ease of breathing and air flow. This balanced coaxial flow valve positions airflow in-line with diver’s mouth for a completely natural delivery. A new, wider exhaust valve minimizes exhaust effort for prolonged comfort. The X650 teams perfectly with the SCUBAPRO MK17 all-water first stage due to lightweight and freeze-resistant components that result in exceptional cold-water performance.