Got a hold of some of these last weekend at a LFS and added them to my sponge filters, and all I can say is wow!!! Endorse the use of them X100000. If it works as good as they say then I will never have to buy another cheap clogging air stone again. Aquarium Co-op sells them (Smalls for $2.00 each and large for $3.00 each). I figure in the long run I spend that on them anyway but will never have to change them again.
Cory thanks for bringing us these great products and keep up the great work supporting this community.