In a world immersed in RF/EMI interference we all need the sound of silence. Nothing makes an audio/video system more irritable than RF interference. To reduce the amount of RF interference entering your system it is recommended that you cap all unused RCA and XLR inputs. You'll be pleasantly rewarded with a blacker background, deeper soundstage, and a richer more satisfying overall experience. These RCA caps come with a box of 10 caps.