Product review (1 stars): The stopper works fine. And the splash guard works as a stopper
The stopper works fine.  And the splash guard works as a stopper, too.  It is too stiff for food to go through it without needing a good solid push.  I tried cutting out a couple of the flaps, but it is still too stiff.
It fits perfect in the hole, which is smaller than the standard splash guard you can buy at Lowe's.