AURA SECOND STAGE REGULATORAura second stage regulators provide a simple, compact design that makes breathing underwater feel completely natural. Aura second stage regulators provide a simple, compact design that makes breathing underwater feel completely natural. This high quality second stage delivers air in a smooth, dependable fashion. Halcyons Aura second stage comes with a single adjustment control and a preset inhalation effort that suits most common diving situations.