Air pump accessory for aquariums: air stone made of quartz sand mixture with extra-fine pores     for extra fine air bubbles. Particularly suitable for the aeration of ponds Air stone easy to connect to the air pump (not included), place inside the pond or aquarium No extra weighting: own weight of the air stone keeps it on the ground For fresh and saltwater aquariums: ball shaped air stone Package contents: 1 air stone, 40 mm diameter, Aeras Micro Ball L