Used CPAP - JUST THE MACHINE - WORKS PERFECTLY! Features Compact Size Provides Exceptional Sleep Therapy in a Small Device Fixed CPAP with Customizable EPR (Expiratory Pressure Relief) Whisper-quiet Operation: Less than 24 dBA Average! EPR & Easy-Breathe Provide a More Natural Breathing Experience Intelligent Tubing Options - SlimLine & ClimateLine Heated SD Data Card Stores Compliance Data for Easy Access Automatic Leak Detection & Altitude Adjustment S9 CPAP EASY-BREATHE MOTOR Quietly Capable Easy-Breathe Motor - CPAP systems create two types of noise: radiated noise in the room, and conducted noise through the tube. The S9's Easy-Breathe motor with axial air-flow produces less "turbulence" lowering average radiated sound levels to just 24dBA. In addition ResMed has reduced conducted noise levels through the breathing tube by 78%. When fully operational the S9 series is no louder than normal breathing! Easy-Breathe EPR - ResMed has updated the clinically proven Easy-Breathe EPR waveform. Breath by breath, Easy-Breathe EPR reduces the work of breathing during exhalation providing a gentler pressure that naturally adapts to your breathing cycle throughout the night.