What is the dress Rachel Bilson is wearing in the Magnum ice cream commercial where she's hopping on the cars?

It was custom made by Karl Lagerfeld. a href="http://www.google.com/url?sa=t&source=productsearch&cd=8&ved=0CH0Q9gIwBw&url=http%3A%2F%2Fjaccofashion.com%2Fstore%2Fproducts%2FPolka-Dot-Dress-Ruffle-Layered-Bow-Accent-Floaty-4-Colors.html&rct=j&q=black%20polka%20dot%20dress%20layered&tbm=shop&ei=Wsj2Te62I4bW0QGfmu2OCw&usg=AFQjCNGoBlwaTFWj5bbub7KX-AF4jbg3Fw&sig2=2mGm2Ko4SHHvqvHrerLjRA&cad=rja" rel="nofollow"http://www.google.com/url?sa=t&source=pr…/a