Cardas Female XLR Caps fit over unused male XLR connectors in your system to eliminate EMI and RF noise absorption. Unlike traditional shorting plugs, these caps do not short the inputs (many pre amps do not like having their inputs shorted). Another difference is Cardas XLR Caps completely cover the XLR input with a solid shield of nickel and brass to prevent both EMI and RFI from entering the chassis through the XLR dielectric. This is a more elegant and probably more effective solution than either shorting plugs or wrapping the plug in aluminum foil. Our caps also protect the XLR from dust and corrosion.