These are so cute and versatile!  I have a size 9 foot, and they fit well.  If your foot is larger than size 9, or wider, the socks may not fit.  Its hard to describe the fabric, but the transparent portion doesnt really stretch.  The black portions of the sock do have some stretch, but not as much as a traditional sock.  I should also mention that the black portion of the sock does have a little bulk, which is good for durability, but not great for really close fitting shoes.  Youll want to wear these with shoes that are a little looser.  The transparent part really seems to be the only really delicate part of the sock.  If you are careful putting your foot in the sock, and wash the socks in a lingerie bag (air dry), the durability is really decent.  All in all, a very current fashion trend for a great price!  Ive revived many compliments, and been asked if they are designer socks.