Halcyon Regulators are extremely reliable and have been used on the longest scuba dives ever accomplished and in some of the harshest conditions; such as the deep wrecks of the Baltic Sea and in the high altitude caves of the Russian interior. The Halcyon H75-P and Halcyon H50-D offer piston or diaphragm first stage options with the Halcyon Halo and Auro downstream second stages. All Halcyon regulator systems are CE approved for 4300psi cold water diving and exceed the CE cold water requirements. To further reduce the risk of regulator freezing in cold conditions, Halcyon's H-50D uses a dry ambient pressure chamber. Meanwhile, Halcyon second stages feature precision molded carbon fiber and technopolymer valve housing and components which also contribute to their lightweight features and corrosion resistance.