I ordered the 23' x 23' and it is bigger than expected. I then ordered 4 of the 16.5' x 16.5" with the 5" depth. The pillows are so small that you actually end up with about an 8" surface,  There is no depth to speak of; If there is a depth the front and back surface should be 16.5" in addition to that. You either have an 8" pillow or a 13.5" pillow with no depth. 

Cons: Mis lead in despription; especially since I already have the larger one and  know what it should be.