This is the Aqua Lung Helix Pro Regulator 1st and 2nd Stages        

First Stage 

• Balanced Diaphragm: A balanced diaphragm provides superior, consistent performance
• Yoke or DIN: Available in yoke (3,300psi/232 bar max.) or DIN (4,350psi/300 bar max.)
• HP/MP Ports and "T" Shape: 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 up to EAN 40 Compatible with up to EAN 40 right out of the box

Second Stage 

• Pneumatically Balanced: Pneumatically balanced for smooth, easy breathing
• Comfo-Bite: Comfo-Bite mouthpiece is soft yet sturdy and reduces jaw fatigue with its unique palate bridge
• Heat exchangers: help to prevent ice forming on the mechanism
• Venturi Knob: Easy control: the in-line ergonomic Venturi knob lets you make precise adjustments, even while wearing gloves