The outer contact is made of a special copper alloy and is 24 carat gold-plated, not only ensuring excellent conductivity but also preventing oxidation, which could impair the contact quality. The inner contact is made of pure, highly conductive electrolyte copper and also gold-plated. This contact is designed in the form of an active spring contact so that the double prism contact surfaces are pressed onto the central pin of the RCA plug by a surrounding bronze spring ring. Not only does this ensure reliable contact with non-standardised RCA plugs but contact also remains reliable even after the plug has been connected and disconnected many times over.