I bought some for Reuger and they're made of flannel material with a thick padding in the middle and they are stitched all over really well. I take a pad with the sticky on the back and cut it in thirds. Then I peel off the backing and place in the belly band so it will cover his little boy parts. There's no pocket for it. It just stays put with the sticky. The ends of the belly band are velcro so it just wraps around him.
Here's a picture from ebay--
http://cgi.ebay.com/LOT-7-DOG-BELLY-...QQcmdZViewItem
I hope that this helps.