Pictured center is a stack of station posts designed for use in applications that receive heavy fog, rain fall and other contamination that is airborne. The idea is that the larger skirts shield the smaller skirts from water as rain fall descends down the insulator (on standard insulators this can cause flash overs if too much water is present.) Even if the smaller skirts become wet, the water which runs off them would self clean the outer edges of the larger skirts below...A win win situation. Having extra surface distance is also a huge plus when contaminants are persistent. Out of the several different post profiles made, I like these the best.