This is the Mares Epic Octopus Adjustable Scuba Diving Octopus

Features:

• Full Pneumatic Balancing Design
• Large Pivoting Purge Button for Fast, Intuitive Use
• VAD Twin Power System: Diver Control Air Flow Responses to Divers Breathing Demands
• Vortex Assist Design (V.A.D.)
• Best Performance Even-In-Most Extreme Conditions
• Compact and Ergonomic Exhaust Tee
• Soft Hypoallergenic Silicone Mouthpiece
• Mouthpiece Provides Less Jaw Fatigue
• 39.4 (100 cm) Superflex Hose with 3/8" Threads
• Weight w/Hose: 17.8 oz. (506 g)

Epic Octopus uses full pneumatic balancing in the second stage, as well as a large pivoting purge button for fast, intuitive use. Combined with the VAD Twin Power system, which allows the diver to control air flow in response to their breathing demands, the Epic Octopus ensures the very best performance even in the most extreme conditions. The Mares Epic Octopus with its vortex assist design (V.A.D.) system: all Mares second stages offer the unique patented VAD system. The air bypass tube conveys air to the mouthpiece creating a swirling vortex with a low-pressure area in the center this keeps the diaphragm down during inhalation, giving very sensitive and easy breathing at all depths. "