The Fly High Air Release plug is a direct replacement for the standard ballast plug (W731) used with Fly High wakeboard ballast bags, but allows you to easily "burp" excess air out of the bag by simply loosening the fitting slightly. You don't have to completely remove the fitting from the bag, and you don't have to worry about spilling a lot of water, just loosen to vent, and then tighten back down. This plug ensures you get the maximum amount of water in each bag. Threading is 3/4".