The Whisper Swivel II is an external exhalation valve with a reusable design that allows for proper ventilation of exhaled waste gas in older models of Respironics masks. While modern masks typically have exhalation ports built into the mask's design, this required component ensured that previous Philips Respironics masks had a continuous leak path in the breathing circuit to get rid of exhaled air.
Sold without tubing. Reusable.