The ResMed AirCurve 10 S is a Bi-Level machine (BiPAP) that delivers two separate pressures for sleep apnea therapy. Users that are prescribed this type of therapy usually have certain conditions that standard CPAP alone cannot alleviate. These conditions can range from trouble exhaling against high-pressure settings of CPAP or the user may have COPD (chronic obstructive pulmonary disease) which can be also difficult on CPAP settings.