Active Aqua Air Stone, Cylindrical

I am not impressed with the largest (2x4") airstones. The bubble production only occurs at around the 1/3 of the stone closest to the nozzle, and the plastic design of the 1/4" connector is flimsy and easily damaged during attachment and removal of the air tubing. The sole benefit of these stones is that they're heavy - they sink to the bottom of the container and stay where they are, which is is something that smaller stones often struggle with.

Great service

seem to work well..this was our substitute when we ordered