The Core regulator&';s amazing breathing, which is rated as "superior" on the ANSTI breathing machine, coupled with its generous features, at an attractive mid-range price, provides the best value of any regulator offered today. The Core comes standard with Aqua Lung&';s unique, patented, auto-closure device (ACD) which seals water out. First Stage Cold water resistant in waters below 50-degrees Fahrenheit or 10-degrees Celcius Auto-Closure Device Prevents corrosive water out of the first-stage inlet by automatically closing as the core is removed from the cylinder valve. This prevents internal lubrication from washing away and is safer for higher proportions of oxygen A balanced diaphragm provides superior, consistent performance Available in yoke (3,300psi/232 bar max.) or DIN (4,350psi/300 bar max.) 2 HP ports (7/16") and 4 MP ports (3/8"), perfectly oriented in a "T" shape for streamlined hose positioning, reduced exhalation effort, and sending bubbles out of your field of view Compatible with up to EAN 40 right out of the box Second Stage Comfo-Bite mouthpiece is soft yet sturdy and reduces jaw fatigue with its unique palate bridge Pneumatically balanced for smooth, easy breathing Venturi Knob Easy control: the in-line ergonomic Venturi knob lets you make precise adjustments, even while wearing gloves Patented heat exchanger dissipates cold caused by gas expansion while drawing in warmth from the ambient water Equipped with a lip shield to keep lips warm This product qualifies for Free Parts for Life