Responsive Respiratory - Disposable Bubble Humidifierdelivers 6 PSI of pressure relief and has a diffuser that delivers therapeutic humidity quietly with defined minimum and maximum water levels. 6 PSI has the ideal safety relief for use with longer tubing lengths. This universal humidifier can be used on a variety of concentrators for all respiratory care needs. Made of durable plastic. Usable volume: 350CC. Individually packaged, Case of 50.