These RCA protective caps could eliminate RF, EMI, RFI in the air and purify the background. The Audiocrast RCA dust caps could prevents and stop dust & dirt from building up in unused open RCA plug jacks. With the RCA protective covers, they helps to prevent oxidation after exposure of RCA socket. These HiFi RCA Noise Stopper Caps are machined into one solid metal shape for exact fit. The middle pin can be removed. These Hi-end RCA caps could beautify the back port to make the interface more regular and beautiful. Package:4pcs In a world immersed in RFI/EMI interference we all need the sound of silence… Nothing makes an audio/video system more irritable than RFI 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.