Interesting. What is the advantage over a standard black eye cup?
first thing that it has an advantage over the standard rubber rectangular eyecup is COMFORT.
being that it is made of chamois, its really soft, and being squishy, it kind of 'molds' itself to your eye socket. So when you're shooting for extended periods of time, it helps to block out unwanted light better than the black eyecup, while also being more comfortable.
it also looks cooler as well. but comfort and extraneous light blockage is my primary concern.
it looks cool though, doesn't it?