The arches are mesh and I tore a ligament in my foot doing zumba.  The bottons really slide and contort your foot in unnatural ways.  Some people have suggested wearing them outside to scuff up so they wouldn't slide so much.  I love zumba, but am out of it for at least 6 weeks.  The sizing for me was 1.5 sizes larger than I normally wear, which I learned from feed back and is true.