Our DUO Sparkling Water Maker is built to last and comes with a reusable plastic carbonating bottle, which is built to carbonate for 4 years and can be used to hold still water forever. The DUO also comes with a glass carafe that can be used to carbonate and has no expiration date. Further, the dual use of the Sparkling Water maker for both indoor and outdoor use allows consumers to go reusable and save thousands of single-use plastic bottles over the carbonating bottle lifespan.