There is nothing I don't like about this product.
The only thing you need to be careful about is the size. I wear 7.5 for dress shoes, and 8.5 for running shoes. I've heard that you need to buy a bit bigger size for Birkenstock so that I bought a size 39. It is almost too big. The next time I will get 38. Get more detail about Birkenstock Arizona Birko-Flor Sandal.