40mm diameter aquarium fish tank ponds ceramic air stone diffusers it is suitable for filteration, ponds aquarium and hydroponic nutrient tanks! * With the sands stone construction fish tank air stone can also be chemically cleaned without the risk of damaging the stone * It produces fine bubbles making it efficient in the replacement of Oxygen in fish ponds, tanks or hydroponic systems. * Size: 40mm(diameter) x 15mm(thick). Inlet Connector Size: approx. 3mm internal, 4mm external. * Weight: 31g; package content: 1 x 40mm diameter aquarium air stone