The low mound design of the air stones provides them with a large surface area with which to produce lots of bubbles and aeration for your aquarium.
Small: 60mm in diameter, 45mm high and has a dual sized inlet that fits both 4mm and 8mm air hose.
Medium: 100mm in diameter, 40mm high and has a dual sized inlet that fits both 4mm and 8mm air hose.
Large: 150mm in diameter, 50mm high and has a dual sized inlet that fits both 4mm and 8mm air hose.