Package includes 2 XLR Noise Stoppers. 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- the bane of dynamics and clarity. To reduce the amount of RF interference entering your system we recommend “capping” all unused RCA and XLR inputs. You’ll be pleasantly rewarded with a blacker background, deeper soundstage, and a richer more satisfying overall experience.