High-quality materials: Our Airlock Fermentation devices and rubber stoppers are made of food-grade silica gel and high-quality plastics, which are safe and non-toxic, and are good tools for the food fermentation. One way valve design: Fermentation bung the one-way valve is designed to isolate air well during secondary fermentation to avoid oxidation, and make the whole fermentation process happen automatically and discharge at room temperature without manual control . Easy to use: just install the rubber stopper with holes on the top of the fermentation container, insert the fermentation bubbler device into the rubber stopper, then pour water into the fermentation airlock device and close the lid to start red wine fermentation. Wide Application: This Fermentation Bubbler device has a wide range of applications. It is an ideal choice for preserving food, fermenting cabbage, kimchi, sauerkraut and brewing wine, beer, mead, etc.