Subaru 2014 Legacy/Outback Owner's Manual page 188

Before Using the Audio and Visual System
■
Irregularly-shaped CDs
• Irregularly-shaped discs, such as octagonal CDs or heart-shaped CDs, cannot
be played. Do not play this type of disc, even with an adapter.
Damage to the player could result.
■
Disc accessories
• Do not use accessories (such as stabilizers, protective seals, laser lens cleaners)
sold for improving sound performance or protecting CDs.
The changes in CD thickness or outside dimensions made by these
accessories may cause problems in the player.
186 Audio and Visual
• Do not attach any ring-shape protector (or other accessory) to the disc.
Although these protectors are commercially available and said to protect
discs and improve sound quality (and anti-vibration effect), in normal use they
can do more harm than good. The most common problems are disc insertion
and ejection problems and abnormal playback problems due to the protector
ring coming off in the disc mechanism.
CD ring