to regain the features of an optical drive, users can either use a separately-available external usb superdrive, or the bundled remote disc software to access the optical drive of another computer. however, this method only allows for disk browsing or software installation; dvd movies or cds cannot be watched or listened to. the remote disc capability is achieved by the computer wirelessly accessing the optical drive of another mac or windows pc that has the remote disc program installed. it can also be used to reinstall the system software from the included installation dvd. remote disc supports netbooting, so macbook air can boot from its installation dvd in another computer's drive. this feature requires remote install mac os x to be running on the remote computer. the software does not allow the playback or information of dvds or cds, nor does it allow the installation of microsoft windows. for these features, an external usb drive is required. a single speaker located under the keyboard is included for mono sound.