The purpose and appeal of your typical rubber duckie is the fact that it floats. Now consider the Gray Concrete Rubber Ducks. Certainly these cannot boast the same ability.
But this does not matter since most of the child-friendly aspects of the odd little objects have been stripped away, except for the adorable form. They cannot be squeezed, they don't make those delightful squeaky noises and they don't flaunt those animated doe eyes and brightly colored beaks.
However, in these images from the 100% Design convention, you'll see that bold coats of paint have been applied to some of the Gray Concrete Rubber Ducks, alluding to the cheerful character of the originals. For an industrialized dose of nostalgia, these marvelous monolithic figures would make lovely iconic decorations in any adult's home.