Yep those are the ones. I've ordered the clay now. Was a bit of a chore looking for natural clay, everything seems to have polyemers in it. I got some das terracotta that said it was 100% natural.Hello, I am not familiar with red ceramic rings, but I doubt it will do anything in the way of giving useable iron to your plants. I assume these rings are hard, baked? Are you talking about what is used as media in a filter?