I saw no mention of a curved plastic tube to insert along the seam of the cover to provide an “arched” opening for the sewn-on cover.  Upon arrival, that tube had been bent to fit inside the box and was kinked. Fortunately, I was able to reshape the tube in order to work out the kink. 
The bed cover is fairly well made and the foam pad fills the bed pocket pretty well. However, the “mattress pad” was not the closed cell foam that I expected from the description (similar to temperpedic foam), but rather one of those egg crate type open cell foam pads. It does provide the dog with good support and she likes it. I guess that is what matters most.