With its sleek contours, compact size, and ultra-light construction the dramatically different S9 AutoSet Auto-CPAP makes sleep therapy truly user-friendly for the first time. The S9's Easy-Breathe motor lowers sound levels to just 24dBA! ResMed's AutoSet technology with expiratory pressure relief continually monitors breathing and adapts, breath by breath, to deliver the lowest pressure possible for comfortable, successful sleep. Add an H5i Heated Humidifier with ClimateLine Heated Tubing for the ultimate in sleep therapy comfort!