This is the Aqua Lung Helix Compact Pro Regulator 1st and 2nd Stages Features: 1st Stage Travel-Ready: the reduced size and weight makes the Helix Compact the ideal choice for travelers 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 HP/MP Ports and "T" Shape o 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 Braided Hose: a braided hose provides flexibility, comfort and excellent transportability Standard Aqualung Parts: since it uses standard Aqualung components, your local dive shop can more easily service it Yoke or DIN: available in yoke (3,300psi/232 bar max.) or DIN (4,350psi/300 bar max.) 2nd Stage Pneumatically Balanced: Pneumatically balanced for smooth, easy breathing Optimize Your Opening Effort: with the "Mini/Maxi" adjustment knob, you can increase the opening effort, ideal for avoiding freeflow at the surface, or lower the inhalation effort, reducing the work of breathing Prevent free flowing: the in-line ergonomic Venturi knob lets you make precise adjustments, even while wearing gloves Comfo-Bite: comfo-Bite mouthpiece is soft yet sturdy and reduces jaw fatigue with its unique palate bridge You don&&';;t need to be big to make a big impact. That thinking inspired the Helix Compact Pro the smallest and most compact regulator Aqualung has ever produced. This amazing piece of technology is equally designed for warm and cold water, meaning it&&';;s perfect for jetsetters on the go, minimalists packing light, and even local divers who simply want unequalled performance per ounce.