An o-ring seal that simply screws into the CO2 valve outlet port with a 5/32" allen wrench. Easily replaceable. Seals better than fiber washers and stays securely in place.
WARNING: This product can expose you to a chemical or chemicals such as Talc, which is known to the State of California to cause cancer, birth defects and or reproductive harm. For more information, go to www.P65Warnings.ca.gov.