Airmax ProAir Membrane Diffuser Sticks are designed to replace the Air Stone Diffusers found on Airmax Aeration Systems. These high-performance pond diffuser membranes are virtually maintenance free and easily screw into your existing ProAir2 or ProAir4 Diffuser Plate via a 1/2″ female threaded end. Each Airmax ProAir Membrane Diffuser Stick measures 6″ in length and is 1.5″ in diameter.