For patients on continuous positive air pressure systems or bi-level pressure systems an exhalation accessory that provides a path for the continuous expiration of waste gas is vital. the respironics whisper swivel ii exhalation port is a reusable exhalation port that provides a continuous leak path in the cpap patient circuit when used with cpap and bi-level machines. the valve is designed to be compatible with the respironics full face mask providing both cpap and bi-level ventilation."