Galvanized steel angle iron posts. Each piece has pre-drilled holes at the ends for mounting or connecting. From dismantled transmission tower. $150 FOR ALL. MAy have a couple of more pieces laying around than what pictures show.
Most are 3 1/2" one is 4" by 1/4" and 3/8"
8', 9',14',15' , the 4" beam is 16' that is the one that is 3/8"