@allenJo - The knock out plug in your car dashboard opens up a whole world of options to you. For example, you can use it for hands free communication. Instead of using your hands to talk on the phone while you’re driving (a big no-no), you can install a hands free telephone system.
This system uses Bluetooth technology and will plug into the knock out plug on the dashboard. It’s the safest thing out there if you need to do a lot of talking while driving. You can talk directly into the system or use a microphone and earpiece if you want.