Philips Respironics EverFlo 5L Oxygen Concentrator (USA) used

This oxygen generator has many advantages that set it apart from all other concentrators. Here are just a few of them:

The quietest concentrator in the world: noise level <45 dBA
Oxygen output maximum concentration: 93+/-3%
The most reliable – can work day and night without interruption
Oxygen purity indication
Operating time up to 40 000 hours
Maximum number of protections and alarms in case of emergency situations – power failure, low oxygen level, clogged filters, etc.
Very robust and reliable design
Very easy to set up and operate
Low power consumption etc.