What purpose do those crazy looking balls serve on high Tension Power Lines

They recently replaced the High tension wires running thru my neighborhood with new higher powered lines which also sit on much taller power poles. see the link for further info

http://www.highlandlf345.info/index.php

Running on the top line of the poles are these crazy looking colored balls and my neighbors knowing I am an electrician have asked what are those balls for?
Well I do not work on high power lines but I still know many things about them and those balls are obstruction notification devices to alert Aircraft to the presence of the wires. There attached to the top wire which is used to protect the high tension wires from lighting.
Since this set of wires go over a valley and we are in an area where low flying aircraft operate either from a small private airport plus Medical Evacuation Helicopters which land in the area during emergency's it is very important they know those wires are there. and that's exactly what those balls do some even have lights in them for at night time.
Tragically several years ago a Gondola Car on an Aerial Tram in Europe plunged to the ground killing all 25 aboard when its wires where cut by a US Air force Jet on practice maneuvers did not see the wires across the valley he was following and sliced the wires.

So while they may look goofy they serve a very important purpose.
There are very specific rules and regulations when it comes to putting up towers and water tanks and buildings of any type
where aircraft might hit them and that includes High Tension lines as well.

If a tower needs to be identified both day and night then you will see a couple of different ways it is done . Some structures are painted with a highly visible orange(red) & White color banding
and have Red lights which blink or stay on constant how many lights depends on how high the structure is. For cases where the painting of band stripes is not wanted or detracts from the structure then white strobe lights are used which some times always stay white or switch to a red light system at night .The FAA Federal Aviation Administration sets these rules as to what is or what is not required and failure to follow the rules can result in thousands of dollars in forfeiture (fines) for not following the rules or maintaining the warning system.