I ordered the small as I am 5' 6" and weigh 110 lbs. The first time I put them on it was hard to reach my waist. Since I have washed them they fit much better.
I love the reflected stripes on them. When I was doing Zumba, the sunlight came through the windows, and they turned from silver to pretty pastel colors.
They don't have as much stretch in them as some of my other leggings, but the quality is great. I can see them lasting a long time.