What is a SodaStream bottle adapter used for?

SodaStream bottle adapters allow standard carbon dioxide bottles to connect with SodaStream carbonators. SodaStream uses a proprietary valve design for its branded carbon dioxide bottles that is incompatible with standard tanks unless an adapter is present.

The primary advantage to using a bottle adapter with a SodaStream carbonator is that it enables the user to use larger carbon dioxide sources than those available from SodaStream. These larger bottles are often less expensive than SodaStream brand bottles. However, many carbon dioxide bottles do not contain food-grade carbon dioxide that is safe for human consumption, such as bottles for refilling paintball and air guns.