40 Plastic Coated Banana Plugs - 4mm (10 Pairs)Solid metal - 24 carat (24 K) gold plating. Banana plugs help prevent corrosion and deterioration of existing speaker wire.The banana plugs will connect up to 3.5mm diameter speaker wire. Speaker cable can be connected easily through the top of the banana plug using a screw to hold the speaker wire in place.The overall length of the banana plug is 40mm and the pin is 14mm long. The pin is 4mm in diameter (like quoted in the title).The plugs can be stacked into the side of one another if required.All the banana plugs are colour coded so you can attach the negative wire (black) to the black banana plug and the positive wire (red) to the red banana plug.Why Buy? If you are using speaker cable to connect your speakers, you will not get the best performance from them as the copper speaker cable will oxidize and corrode over time, by using a banana plug you can prevent this from happening. They are extremely easy to install and not only do they improve the sound quality, they allow you to quickly plug and unplug speaker cable into the terminals. To attach the plugs to the speaker wire, the speaker wire should be stripped, inserted into the banana plug and the screw tightened until secure.Most systems nowadays are jam packed with cables running everywhere. It is usually very hard to properly insert speaker wire into terminals and to get them tight enough to hold the speaker wire in place. Also, if great care isn’t taken when inserting the speaker wire, stray copper strands that aren’t inserted into the terminal properly can potentially touch other terminals and cause shortages resulting in permanent damage to your system.These banana plugs help to create an extremely high quality connection. They can be used with speakers that have binding posts in the back of them and they are perfect for top of the range equipment. They are a great finishing touch and best of all they’re a bargain!.