Plugs have a friction clip to securely hold the housing when mated. They also have an alignment key that ensures the plug and housing are mated correctly, which is helpful when you can’t get a good look during installation. To install the plug on your circuit board, push the contacts through the board’s holes and solder them in place. The pins are gold-plated brass, so they resist corrosion better than tin- or nickel-plated pins. This means they’ll have a good, long-lasting electrical connection.