Instruct: Classify Amazon reviews into positive or negative sentiment
Query: They work!

I used to ALWAYS end up with edema in my legs after even a two-hour flight. But on a recent flight from Atlanta to Buenos Aires--which was for TEN hours--I wore these Jobst knee highs during the entire flight, and survived the flight without any edema whatsoever. Finally, I found something that prevents water retention. From now on, I'll wear them every time I'll have to be sedentary for some time.