Bought Cog I, Cog II and Cog III as shown in the picture.  Absolutely LOVE these pieces.  Had some trouble with getting them shipped to us, some of it was lost in the first go around, but Wayfair came through and shipped us the lost items right away.  We get so many compliments on this arrangement.  They took a little time to get them hung properly, but well worth it!!  Would definitely recommend buying at least the set of 3.