Thanks. Maybe I should have been more clear. I use CPAP but don't use O2. I have a 5 LPM concentrator that I am trying to figure the best way to hook up to maximize the FiO2 at the mask in the event that me or my family get COVID-19 and the hospitals are overwhelmed.

I am trying to figure the best way to get the maximum O2 from a 5 LPM concentrator into the CPAP mask. I do have the Oxygen Adapter Enrichment Port Connector but had also seen some info on making a reservoir like this;

https://www.youtube.com/watch?v=lSxyUZHCaac