Birkenstock are great for summer but they are often expensive. for 30 euros, it's okay. I took them in mocha color. they have a smooth finish and are really comfortable. it's true that it's not a very sexy model, but this is not what we want in Birk. I will not leave this summer :)
otherwise, I saw amazon had put a message for size. indeed, I took a size smaller and they fit me well (model "narrow"). thank you board!