Reduced Maintenance Adjustable Bubble Size Weighted to Sink These are one the best air stones out there that money can buy. They are weighted to sink naturally and can be taken apart if they ever were to clog - so they can be cleaned or the disks replaced. They also work great inside sponge filters. Instead of replacing a cheap ceramic air stone every 4-6 months as they get worse and worse for bubbles, install one of these once and nearly never worry about it again. Tighten or loosen the disks to change how big the bubbles are. Tightening the air stone will make bubbles more fine. This, in general, causes better lift for sponge filters and better oxygenation of the water. However, this can use up more of your air pumps bandwidth as it's putting more restriction on it. Comes with 3 replacement disks if the original disks become dirty. Or you can add extra felt disks if you're pushing an abnormal amount of air through 1 air stone. You will need to tighten them quite a bit to fit them all on and it will be very fine bubbles, not recommended in normal operations.
