6 inch Ground Plane Disc for Antenna Mounting on Aluminum Fiberglass Plastic

6 inch Ground Plane Disc for Antenna Mounting on Aluminum Fiberglass Plastic is designed for vehicles with non-metal roofs and ground plane antennas. Optimal performance is achieved when mounted on top of the roof, with the antenna atop the disc, but it can be installed underside with potential performance decline. The disc has a diameter of 6in, an alloy construction, and 4 3/8in holes for incremental antenna positioning adjustment.