Adapter is used to mount Beacons & Globes to other poles. Adapter Plug is used on the Fiberglass poles to adapt to Lights to Pole Top. Strong Nylon Adapter fits in the End of the Fiberglass Flagpole, allowing Beacons & Globe Lights to be threaded into the Fiberglass pole. The Adapter Plug pushes into the Top of the Fiberglass Pole then the threaded Stem will screw in. 1/2″ -13 Thread. Due to manufacturing variations of poles, some light sanding maybe required to the Adapter for proper fit.