Abe I'll take one.
I bought a similar product many years ago at Valley Forge, it was made of mouse pad foam.
Used properly on new cloth you can rack the balls without a rack, just roll them together by hand, these things really work.
There is no magic to a tight rack - a quality set of balls racked in the exact same place every time is all there is to it.
It kills me watching people squeeze the balls as hard as they can when racking - you can't fix stupid.
Mark your cloth with a pen or pencil and mark the triangle so it is put into the exact same place and turned the same way each time if you use a cheap and maybe not symetrical triangle.
If the balls are not the same size its impossible to get a tight rack.