I actually use the small bags that SeaLife puts 5 moisture munchers in when they sell them. If you buy a 10 pack, they pack 5 in each inner (small) bag and put 2 small bags in a bigger, outer bag - or at least that was the way they sold them several years ago. I haven't bought any in over a year, so they may have changed the packaging, even before they went to the newest "sealed" packages.
I am just reusing what they previously sold - they were nice thick bags - but the seal was hard to get fully closed. Another place I have gotten small bags (about 1" x 2") with seals is the ACE hardware store - they have them to put loose screws and nuts in - they are fairly light weight, but seal better. They hold 4-5 moisture munchers.
Hope that helps