SoCal Flying Monkey’s 2022 review of the Mountain High O2 D2 pulse-demand aviation oxygen system shows the portable 4-person kit raised passenger SpO2 from mid-80s/low-90s to mid-90s/upper-90s on flights around 9,500–11,000 ft. The system conserves oxygen by delivering pressure-altitude-adjusted puffs, claims a 48 cu ft tank runtime of ~83 hours single-user (~20 hours for four), and includes safety alarms and headset boom cannulas; the reviewer reports elimination of nausea and fatigue linked to hypoxia.