Nasal Pillows vs. Nasal Masks at High CPAP Pressure

Inclusion Criteria: * Patients willing to give written informed consent * Patients who can read and comprehend English * Patients being treated for OSA for \>6 months * Patients ≥ 18 years of age * Patients using nasal mask systems with fixed pressure ≥ 12 cm H2O * Patients who can trial the trial masks up to 14 nights * Patients naive to pillows mask systems Exclusion Criteria: * Patients using an inappropriate mask system * Patients using Bilevel flow generators * Patients who are pregnant * Patients who have a pre-existing lung disease/ condition that would predispose them to pneumothorax (for example: COPD, lung cancer; fibrosis of the lungs; recent (\< 2years) case of pneumonia or lung infection; lung injury)