I was an investor with a company that made cd rings ( does not matter the company or particular product ). I lost some money. I am a believer in green markers on the inner and outer edges of cds and dvds ( dvds were not available at that time ). The engineering team behind the production of these rings claimed 2 specific reasons for the benefits and enhancements heard ( yes I heard them ). Based on memory : ( 1 ) The light of the laser was contained within the boundaries of the cd. Greater intensity of the light created a better " read " of the zeros and ones, eliminating the need for interpolation ( read up on it ). The green markers do the same. And yes, green sounds the best, ime. ( 2 ) The outer edge of the cd was prone to vibration, and the application of this ring minimized this vibration. Again, to maintain a better " read " of the zeros and ones ( the information ). Many after market devices were developed to minimize these vibrations, and the transports from various companies became popular for the same reasons ( Pioneer’s stable platter, and the majority of top loaders with their weights and pucks ). Transports are " significant " in their ability to get the information off the silver disc, and, ime, as significant ( or even greater ) than the outboard D/A converters used after them. Just some information to those who might be interested. Enjoy ! MrD.