Usually I’m skeptical when I buy something off eBay, especially when it’s cheap and from a no-name company. This CO2 diffuser which is sold by U-Barn makes the tiniest microbubbles which helps the CO2 disperse evenly and makes for more absorption into the water. I will never go back to glass diffusers!!
Ebay link: http://www.ebay.com/itm/271037310439