This new premium washer is precision injection molded from nylon. The most common washer for this application is made from a fiber material called “Fish Paper”. The change in material from the fiber to nylon in itself is significant in the washer’s ability to seal. The washer has a sealing ring molded on each side that further aids its sealing ability. Also, three small, thin fins were added to the perimeter. These fins self-center the washer in the CO2 fitting and help to hold it in place while the fitting is being coupled to the CO2 tank. This exact positioning ensures a gas-tight seal every time. These improvements addressed all of the complaints I had heard from end users in regards to these washers. Ensuring a perfect seal every time is also extremely important because these tanks can cost $85 or more to refill, not to mention that an empty tank can mean lost business for end users. Leaks are very costly. Premium washers are not.