This is a 7" Diffuser Airstone with a 1/2" male NPT fitting that fits our Airstone Foot Valve which is also called an Backflow Valve as shown on this page.
The Outdoor Water Solutions airstone is a critical component in the successful aeration of a pond or lake. The airstone turns air into thousands of tiny bubbles so that oxygen can dissolve into the water and improve its health. Diffusing air into water can increase its effectiveness by over 1000% - This is definitely a secret ingredient for efficient aeration. Dimensions 2.25 x 7", 3.5 lbs.