Mares Carbon 42 Carbon Fiber Scuba Diving Regulator VAD (Vortex Assisted Design) by-pass system for effortless, natural breathing under all conditions DFC (Dynamic Flow Control) for improved performance at any depth Oversized purge button is extremely easy to use, even with heavy gloves Specially designed mesh grid 2nd stage cover to prevent unwanted free-flow even in the strongest currents Nitrox Compatible to 40% (The Recreational Limits of Nitrox)