The Sound Improvement Disc is an accesory that is placed on top of the CD, resulting in a better separation of instruments and a much clearer reproduction of the voice. The best way to hear the difference the SID makes to the sound is to play a piece of well known music for a maximum of 30 seconds without the SID, and then the same piece with the SID in place.

The SID disc has a special matt finish on one side and this side is placed down onto the CD label, so that the stray laser light is absorbed, the green colour changing the red light of the laser into black thus neutralising it. Using the SID will stop the false information being read by the laser correction system resulting in a greater resolution and a much smoother sound. The SID comes in 2 versions, Model 14 for Phillips and Sony transports, Model 15 for certain top loaders and players with Pioneer stable Platter and Meridian 506 and 508.