The regulator of choice for the most formidable of divers. The Xstream works with air, nitrox, trimix or 100% oxygen. Certified for use down to 200 m / 656 ft, this regulator never quits, giving it the honored place as the US Navy’s, US Coastguard’s and the NYPD’s preferred regulator.Poseidon Xstream first stage has a built in anti-freeze protection in its construction. TDA (Thermo Dynamic Antifreeze) ensures that the through-flowing water keeps the ice away, entirely without fluids or extra diaphragms. No extra environmental sealing required.