Being a flat lander I start my Mountain High EDS unit at 5,000msl which is usually below field elevation out west. I just sent my O2D1 unit and regulator to MH for its bi-annual winter checkup and refurb. Cheap insurance for a critical flight system IMHO.

Did you know that these units alarm if there is no O2 flow (you stop breathing or the tank is empty). You should get one.

Soooooo, did you know that MH sells refurbished (1st generation) O2D1 and O2D2 units at about 1/3 off of the price of a 2nd generation* new unit? There are even some of the original D1A units that come up for sale at almost 60% off of new. I don't believe that MH sells refurb units to make ends meet. I think they do this as a company policy to save pilot's lives. You should get one. My $0.02.

See https://www.mhoxygen.com/350-eds-closeout/

Enjoy,
John OHM

* Anyone know what the difference is between the 1st and 2nd generation units besides the layout of the controls and more colorful graphics? Thanks.