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.Comes with easy-mount suction cups.Standard pressure 0.01 MPa, Max pressure 0.012 MPaChoose from two versatile, round air stone disc sizes. This one is 4" in diameter and 1" tall. Has 3/8" diameter inlet.