Alternative zum Mountain High-System und batterieunabhängig:

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%.

https://www.preciseflight.com/general-aviation/shop/product/preciseflow-demand-conserver/

Funktioniert einwandfrei (bis FL180 getestet) - habe aber keinen Vergleich zu Mountain-High-Geräten

Nachteil: Preis ($ 899/Stck.) , jeweils nur "single-use" möglich, d. h. für 2 POB -> 2 Geräte erforderlich