The airlock, or otherwise known as a fermentation lock, is commonly used in beer brewing. It allows the carbon dioxide that is created during the fermentation process to be released from the fermenter while also preventing air from entering the fermenter. This in turn avoids oxidation. This popular 3-piece airlock mounts on top of the fermentation vessel, and allows for a broad range of pressure equalization. Most commonly, one will fill it to the line with either boiled water or sanitizer. This plastic airlock easily comes apart for cleaning, and is a necessary utility when it comes to the perfect fermentation process.