ResMed AirCurve 10 Auto BiPAP machine and its accessories. Main device: The grey unit on the left is a BiPAP machine, used to treat sleep apnea by automatically adjusting pressure for inhalation and exhalation. Accessories: The carrying case on the right contains a white breathing tube (circuit), used to deliver pressurized air to the mask. Humidifier: This model series typically includes a built-in "HumidAir" heated humidifier, which adds moisture to the air for increased comfort.