Primacoustic IsoPlane Foam IsolatorThe IsoPlane foam monitor isolation pad is designed to decouple the sound from the loudspeaker so that it will not resonate with the desk or shelf. This helps reduce an effect called comb filtering that occurs when various frequencies add or cancel with each other when coupled. The IsoPlane can also be used to decouple turntables and other devices that can be adversely affected by sound resonating through the floor and furniture. Sold in sets of four