An airstone, whose purpose is to gradually diffuse air into the tank and provide oxygen for fish to breathe, is a necessity to have around your aquarium if you are a lover of aquatic animals. It?s also a must have for Hydroponic and Circulation system. Padmashri air stones are made of high quality non-toxic mineral material. With high temperature sintering, stones are sturdy and durable, have high dissolved oxygen rate and create even and tiny bubbles rather than a limited number of large ones.