Product review (5 stars): great for what I needed it for
I used this so that we could rearrange a hutch to a different wall and not block the vent.  First- the product is sturdier than I thought-  will it tolerate being stepped on?  I would say no- however it isn't going to fall apart apart on its own.  It is sturdy enough to do what I needed it to do.
The floor vent was larger than this product so I had to use duct tape to shrink down the size of the vent and I used it to secure it to the vent and hold it in place.  It works very well and I am pleasantly surprised at how much airflow we get out of this vent now.
Mine came with two pieces-  one was fitted to go over the vent- the other would slide over the first piece to extend if you need it to.  Mine also included one binder clip.