The internal plastic support bar is easily remove able by our seven month old pups and then destroyed as it becomes their chew you.  Such has been the case with both if these that we had purchased.  Furthermore, upon removal of this piece in our Cotten model, we also have the microfiber one, the seam came apart at the chew point where the plastic bar was pulled out.  A zipper would be a far better design improvement and worth an extra $5 at retail.