The new Forte banana plug section is designed to maximise contact area throughout the wide tolerance range encountered in 4 mm amplifier and speaker sockets. Some can be quite tight whereas others may be loose, so the spring loaded Forte blade is designed to fit into smaller and larger sockets with equal insertion force. This means that the contact area is maximised and the connection remains uniformly tight.
Screwloc spade plugs are ‘duo’ to enable secure contact with both standard and wide spade terminals.
Both the banana plugs and spades are made of brass which has roughly twice the resistivity of copper. For this reason the plug was devised so that its cross-sectional area would be at least double that of the cable to which it was connected effectively cancelling out the extra resistance of the plug material. QED then plates the connector with high purity gold which has a resistivity almost as low as copper but more importantly does not oxidise in air.