CDRs are disc images created with Mac OS X’s Disk Utility application. Other common disc image formats include DMG and ISO. Disc images are copies of physical discs that keep the exact file structure of the original. The Mac OS X operating system recognizes disk image formats such as CDRs. To view the contents of a CDR, or any other type of disc image, you must mount it to the desktop.
Navigate to the location of the CDR file in the Finder.
Double-click the file. The CDR mounts to the desktop and the contents open in a Finder window.
Click the disc icon in the upper-left corner of the Finder window under “Devices” to reveal the contents of the CDR if you navigate away from it at any point.