The present invention provides a device comprising an intragastric balloon, comprising: a polymeric wall a valve system a casing a sealing member and a deflation component. The casing has one or more vent pathways, and the sealing member is positioned to block the one or more vent pathways when in place. The deflation component is situated in the casing and behind the retaining structure. The deflation component is configured, in use, to expand upon exposure to moisture inside of the balloon via the one or more vent pathways, thereby pushing the retaining structure and thus the sealing member linearly past the casing to open the one or more vent pathways so as to provide fluid communication between an in vivo gastric environment and a lumen of the balloon.
