The stackable floats are 3' x 4' x 20". The upper float is foam filled for flotation of the structure. The stackable empty float is bolted to the bottom of the float and is filled with water. If needed, a second water filled float can be added. This system adds only the weight of the shell to the dock. The encased water acts as the attenuator against waves. It is an inexpensive and effective way to deter waves. The picture shown below shows a wave attenuator dock on Lake Erie. Notice the large swells on the right of the dock, compared to the left.