Our Outdoor Flagpole Aluminum Ball Ornaments are unsurpassed in beauty and craftsmanship. If you're not sure what size you need for your flagpole eagle or ornament, it should match the diameter of the base of your flagpole. If you need help just give us a call! The spindle threading will secure the flagpole eagle or ornament into the top of the flagpole or the top of the flagpole truck. The size of the spindle threading is 1/2".