I'm a 63 year-old man who has just been struck with another round of cluster headaches. In order to treat them, I recently bought this oxygen concentrator from Direct Home Medical: https://www.directhomemedical.com/millennium-m10-10liter-oxygen-concentrator.html. One of their major competitors told me that the unit would cost $2,000 and might take 2-4 weeks for me to get. The sales reps with whom I spoke at Direct Home Medical were extremely helpful, answered all of my questions, and got the unit to me in 48 hours. The cost was only $1075. Their care team followed up with me the same week and answered the only question that I had about how to use the machine. The machine itself has been extremely effective so far, aborting my cluster headaches in 10-15 minutes. I'm delighted with the machine itself, with the price, and with the service that I've gotten from Direct Home Medical, and I'd certainly recommend the company to others (and in fact already have, when someone told me last week that her mother suffers from the same malady that I do).