Pilot tested and pilot approved! The X3 Demand Conserver is the best demand conserver in the aviation industry. The X3 Demand Conserver is the only fully mechanical demand conserver (no batteries required). By giving you oxygen only when you "demand" it, the X3 will extend the duration of your oxygen supply by at least 300%. The X3 Solo Pack includes everything you need, including a dual lumen cannula, dual lumen mask, connectors, and tubing. The X3 is STC'd for Cirrus and certified up 25,000 feet.