The Mares Ultra Adjustable Octopus Regulator is designed for use with the Mares Ultra Regulator Series. 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.