Active Aqua Air Stone Cylindrical 2" x 2"Description Product Details: Active Aqua air stones are an ideal way to add oxygen to your hydroponic growing system. The micropore design energizes the growing solution as it aerates and circulates nutrients. Air stones will extend the life of your nutrient solution, help keep roots healthy, and promote exceptional growth. Choose from three versatile cylinder sizes. This one is 2" long by 2" in diameter, the medium sized cylindrical air stone.