This Kegco O-Ring is made for use with Ball Lock tank plug for Cornelius Home Brew Soda Kegs. This green replacement o-ring can bring your draft beer keg back to life. Because O-rings deteriorate over time, they need to be replaced in order to receive the best performance from your kegs. Kegco offers a variety of colored o-rings to provide and easy way to identify your various brews and sodas.