Cast aluminum construction with cast nylon pulley. Designed to slip over the top of a flagpole and secured with stainless steel set screws. The top of the truck is designed to accept an ornament with a spindle threading of 1/2″- 13NC. The ornament is secured to the truck with a stainless steel screw.The size listed is the diameter of the flagpole the truck will fit. Example: The 2″ size truck will fit a pole with an outside diameter of 2″.