Thank you for viewing. This is the "AG407TNS TV-NAVI Switcher for Commercial Navigation Systems," which allows you to switch between TV and navigation functions. It came with a used navigation system I purchased. There are no instructions. I don't know how to use it, and I don't plan to use it in the future, so I'm selling it. If you have any questions, I can add more photos, so please feel free to ask. We are looking forward to your purchase if you understand that this is a used item.