This is great. It has helped me in keeping my smaler fishies from getting in the tube. I have the baby biorb, and recently just purchased a blue-eyed yellow bristlenose pleco, which he loved to go into the tube where the airstone is. I was worried that he wouldn't get out so I got this to prevent him from getting in there. My shrimp used to go inside the airstone tube as well as some of my smaller cardinal tetras. NOW I don't have to worry about my fishies getting in there or getting stuck in the tube nor getting into the filter by accident. Awesome product. This product should come with the biorb tanks as a regular necessity item.
Pros: prevents my fish from getting in the airstone tube, prevents my fish from getting into the filter
Cons: should come with a unit when you purchase a biorb!