swallowing air (usually followed by belching and discomfort and flatulence)

swallowing air (usually followed by belching and discomfort and flatulence)

characterized by or allowing admission

reactive or functioning or allowing movement in two usually opposite directions

reactive or functioning or allowing movement in two usually opposite directions

reactive or functioning or allowing movement in two usually opposite directions

reactive or functioning or allowing movement in two usually opposite directions

reactive or functioning or allowing movement in two usually opposite directions

reactive or functioning or allowing movement in two usually opposite directions

reactive or functioning or allowing movement in two usually opposite directions