Swell Flat Round Airstones can be used in either aquariums or ponds. The air stone diffuses the air from the pump making lots of tiny bubbles (rather than large ones) which creates better saturation and more oxygen for your fish.
Swell airstones are great value compared to bigger brands and are solid reliable airstones which are very weighty and sturdy.
Sizes available (diameter):
Inlet size: 4mm, for use with 4mm hose.