I also have this one that I would sell for $7, including shipping and paypal fees.
This one is easier to use because you don't have to take it all apart to change pads like the one listed previously.
http://www.petsmart.com/product/inde...amily&keepsr=1
If you are using paper pads the frames definitely do help, but they are not foolproof. Some dogs will still get the pads out with any kind of frame/holder.