For sale, 5-liter oxygen concentrator. Used twice. • - Oxygen concentration above 90% and better therapeutic effect for patients with pulmonary fibrosis. • The device is equipped with a humidifier bottle with a pressure relief valve for more comfort and ease of use. • Four flexible wheels for easy movement or positioning in any direction for more comfortable use. • - Oxygen flow rate from 0.5 liters to 5 liters. • Simple operation and easy-to-read LCD screen. • There are alarms such as high and low pressure alarm, low oxygen generation alarm (power outage alarm). The device has filters (bacterial filter) - almost no sound, as the sound level is 38dbz. • There is a HEPA filter & and a bacterial filter, and the device is very lightweight.