A full face mask seals around both the nose and mouth and is held in place with straps, or headgear. Full face masks are a good alternative for people whose mouths tend to drop open unknowingly during sleep. When the mouth drops open the treatment pressure blowing through the nose via a traditional nasal mask escapes, rendering CPAP therapy ineffective as the pressure intended to hold a patient's airway open flows out of the patient's mouth. The full face mask equalizes pressure between the nose and mouth allowing the patient to receive the proper treatment pressure at all times.