And to act a visual location for the lines there located on so they don't fly into them.
The ones I've seen have been on lines that stretch a long distance between towers, like over major Interstate, or a lake, even from one ridge top across to another.
Basically any place where an aircraft might fly low or to land.
Charles
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Metal is the material, The forge is life, The anvil and hammer bring character and soul.
When the transmission lines cross the river with long span the sag of the conductor is more and these colourful balls mostly reflective are used not only for air craft but also for water ways. The reflection is also visible during heavy foggy days.