The ResMed Side Cover is an optional accessory designed for use with ResMed's AirSense 10 CPAP, AirStart 10 CPAP, and AirCurve 10 BiLevel Machines. By fitting over the humidifier chamber slot, it allows the machine to be used without the built-in HumidAir Humidifier. This Side Cover is easy to install and lets you customize your machine to your specific needs.