AVAILABLE OXYGEN
Sorry I haven't been monitoring this website lately but....
A regular medical supply, or repair center may not be able to advise you on a modified concentrator, they have no idea of the types of modifications that have been done, I am sure your M-15 or M-20 did not start out as such, it started out as a factory stock M-5, or in other words, a 5 lpm concentrator, I can answer any questions, I used to modify these concentrators for UNLIMITED OXYGEN and EXTREME OXYGEN, I was their lead technician, but had no control over their customer service.
Please feel free to contact me with any questions, I have been in business for 9 years now, and still going,
availableoxygen02@yahoo.com or call 317-412-3356