I have purchased New Balance footies in the past and really liked them, the fit was perfect and they didn't pull down in heel area.  These, however, are extremely tight in the midfoot-arch area which does, on the plus side,  prevent them from slipping down in heel area but causes them to just hug too tightly.  I have a small foot and don't have a swelling problem.  In addition, they are too short and pinch the toes; wearing a shoe size of 8-1/2, these socks labeled to fit 8-10 should not be a problem.  I washed them and air-dried them for fear they would shrink.
  In addition,  your toenails can pull loose some of the elastic threads on the inside of the sock.  Did like that they are a thin sock which would be nice for hotter weather but won't be buying more.  Had bought a pair of Wrightsocks at a local store which have similar features but wasn't thrilled about the $11 price per pair, however, they are far more comfortable and fit great so guess I'll spend the extra money to get the quality.