uxcell Plastic Aquarium Fish Tank Striped Air Tube Airstones 4mm 4pcs Colorful Increase oxygen levels, lower CO2 and raise pH. Total Size: 13x 9 x 1.5; Stone Size: 15 x 43mm / 0.6" x 1.7"(D*H); Connector Size: 4mm It is an important instrument to successfully keep aquatic fish for respiration process. It produces fine bubbles making it efficient in the replacement of oxygen in fish ponds, tanks or hydroponic systems. It creates a circle of bubbles that helps keep healthy fish and adds to the beauty of the aquarium.