Small size large capacity Inteliegent machine with low noise for home and travel AC 110V

I need oxygen 24/7 because I have both COPD & Sleep Apnea. The main unit resides in our Master Bedroom which is upstairs. I also have a portable (pulse) unit for out & about. The insurance won’t cover a third unit & I felt that I needed a continuous flow unit downstairs. After due diligence, I bought a Dedakj DDT-1L from Elehealthy because initially, I couldn't find it on Amazon. Apparently, Elehealthy scraped (stole) the reviews from Amazon so hopefully this review will eventually get to their site.When the unit came, I noticed right away that the oxygen outlet was plastic, molded as part of the case. The more expensive units have a metal outlet. As feared, the plastic outlet broke within the warranty period. The warranty process is slow & painful. On 06/28/21, I sent, as requested, a photo of the breakage. On 06/29/21, I received an email saying that the situation was under review & that I would receive a reply as soon as a decision was made. As of this writing, I haven’t heard from the factory or the supplier if the unit is covered. I finally wound up repairing the unit by myself. It was certainly faster than sending the unit in for warranty service AT MY EXPENSE! For the repair, I used a metal outlet adapter which, I noticed that the new units now have.The Owners Manual is available from the manufacturer’s or supplier’s site as a download. I would suggest that you download it & read it carefully as this unit delivers a smaller percentage of oxygen as the liters per hour (LPH) is increased.PRO’sAt $360.00 delivered, the unit is about a third of the cost of the more expensive models.It’s smaller & lighter than most oxygen concentrators.It has an active display that contains useful information. Control of the unit is local or is controlled by a remote (I love the remote control).Has a built-in humidifier.Will supply negative ions which can be turned on or off.Has a timing function which, can be useful.The noise level, advertised at 45dB, is about the same as the others although, it's a bit quieter than other brands that I’ve used.CON’sAs the volume goes up, the percentage of oxygen goes down. The expensive models have a constant percentage of oxygen (Typically 90%) at any setting & Dedakj does make a model (about $900.00) that will compete with the big boys.The Negative Ion generator is electric (which means Ozone). Although, I suspect that some water generated anons are generated in the humidifier.The humidifier tank has to be refilled almost daily & my guess is that the O-Rings used to seal the humidifier will be the first item to wear out. I typically run the unit at 2 to 3 liters/Hr. Which, provides an oxygen concentration of 50 to 70%. It hasn’t been a problem. Being a constant flow unit (PSA), I can recover much faster when needed, as opposed to using a portable (pulse) system.FWIW: I deal with cannulas, oxygen lines, adapters, etc. on a daily basis. I have never broken a part or had one fail until this event. When I needed service or replacement of the other concentrators, turnaround was only a couple of days & at no cost to me. I don’t use the Anon function because the negative ions are electrically generated.