Not lightweight socks.  I bought these hoping for a lightweight sock than can be worn in a shoe.  Instead they are a medium weight sock meant for an athletic shoe (sneaker).  They have an exterior layer (grey) and an interior layer (white).  Double the thickness I was hoping for.  They are suitable  for hiking shoes or boots, but too thick and heavy for summer wear.  Might turn out to be a good cold weather sock, but not the type of sock I saw in the description on amazon.