When the produced by the items sealed inside the bag reaches a certain pressure, the could push the venting valves opens from the insides out, venting excess outwards; when the pressure inside the bag decreases to an insufficient levels to open the valves, the valves automatically closes Using this single way degassing valves helps ensuring the freshness of your beans You can also smell the aromas of the coffee directly by squeezing the bag, which helps you better verify its freshness Easy installation: Crafted from food grade with excellent temperature and resistance for consistent function Our single way degassing valves requires none heat sealing, has strong adhesion, is not easy to fall off, and can be used immediately after application, making it and efficient This adhesive strips type exhaust vent valves is suitable for attaching to the surfaces of containers requiring single way exhaust, such as coffee bags, food bags, packaging bags, pet food bags, kimchi jars, fermented feed bags, tin cans, and cans