Keep airborne EMI and RFI noise out of unused female RCA jacks and do it in style with Cardas Signature RCA Caps. Cardas Signature RCA Caps are functionally identical to standard RCA Caps from Cardas. But Signature Caps sport a designer look. They fit over unused female RCA connectors on the back of an amp, preamp, receiver, and other components to eliminate EMI and RF noise absorption. Unlike traditional shorting plugs, these caps do not short the inputs, and many preamps don't like shorted inputs.