Breathing underwater should feel natural and that experience is one of the things that most clearly separate Halcyon second stages from our competitors. As soon as you experience the smooth, high volume of air delivered by a Halcyon second stage you will be hooked. Our high quality second stage regulators provide diver adjustable controls for the ultimate in breathing performance.

• Halcyon’s Halo second stage offers steadfast reliability and impeccable performance; two methods of breathing adjustment make it the top choice for demanding Halcyon divers.
• Balanced, downstream valve offers incredibly smooth breathing in all conditions. The design slightly offsets the force of the downstream air entering from the first stage, allowing reduced spring tension and a decreased inhalation resistance. Halcyon first stages are balanced, so the Halo is a perfect fit with either the H-75P or H-50D Halcyon first stage.
• Adjustable inhalation control refines breathing effort by way of an easy access control knob; this allows the demanding diver an opportunity to fine-tune the air delivery of the second stage. Meanwhile, our Aura second stage features a pre-set inhalation effort that suits the most common diving conditions and can be fine tuned by an Authorized Halcyon Dealer.
• Air Control Vane (ACV) offers a second diver adjustment for the ability to fine-tune breathing. The ACV uses vacuum assist technology to reduce work of breathing and increase diver comfort. This level of refinement is available on all Halcyon second stages. ACV in _diveÓ position gives powerful breathing support while ACV in _HalcyonÓ position helps prevent free flows; this can be helpful on the surface, when diving in currents, while scootering, or when the Halo is used as a backup regulator.
• Comfort mouthpiece is standard on every second stage to reduce jaw fatigue and mouth irritation. This long lasting mouthpiece requires only a minimum effort to hold comfortably in place. In combination with the freedom of head movement provided by Halcyon_s primary long hose, you will enjoy dives free from the jaw fatigue common with certain mouthpieces and/or poorly balanced hose routing