They are very deceptive on their products. I purchased a portable unit from them for a friend and I paid extra to get a second battery with it so she would have a battery life of 120 minutes for each battery making it a 4-hour charge with 2 batteries. Of course, you pay more money for the second battery, but I figured it would be worth it if you run out and cannot breathe to have a second battery to slap in and continue on.
Come to find out, the unit I bought only runs for 20 minutes and stops.
I emailed the company to address this issue and they came back with a Bull Ship explanation that has no medical value, but it explains the way they scam you on this little paper weight. Below is my email to them and their response in an attempt to get me to spend more money with them on a new device they claim will do what I want.
In conclusion. Do not waste your money on this item which comes direct from China, and no one sells them in the USA. If you want to return yours within a 30-day period, you pay the shipping back and have to wait 30 days plus, if even then you get your money partially refunded but reading their return policy says if you used it, they will not take it back, and everything MUST be in its original packaging unused. So, trying it out makes it used.
Their reply to me:
We wrote on the product details page that the HC-30M works in intelligent oxygen therapy circulatory system: one intelligent oxygen therapy cycle time is 20 minutes, which means it will stop after 20 minutes of work. If you need to work continuously for 24 hours, you can change to other models, please check this one.