High performance diffuser provides small bubbles for quiet operation with high humidity output 2 psi audible-alarm pressure relief valve to vent excess pressure for additional safety DISS female connectors in metal construction for maximum strength and durability Polycarbonate shatter-resistant bottle for maximum durability and service life Transparent jar provides full visibility of jar contents Produces minimal noise helping the patient rest comfortably 360º DISS swivel connection for easy installation 135 ml capacity at maximum fill line