The external GPS antenna. It has a magnet base and two screw holes. In my case I've used the gaping hole where the AM/FM radio antenna was. There happened to be one small hole behind the larger one, so I used that to install a screw to the antenna. The magnet basically holds it down with the screw being the security. I used a bit of alligator grommet on the edge of the hole to protect the cable. Then I ran the cable through the same rubber grommet in the fender to the cabin.