I have been wearing SmartWool PhD low cut socks for a few years and they have worn out much more quickly than I had hoped so I gave these Carhartts a try.  I wear a size 10.5 and the Large fits great.  They are snug fitting, come up to just the right height, and feel great.  My first impression is that they are easily on par with the SmartWool socks, but a few bucks cheaper!  Only time will tell how durable they are but on first fit I give them 5 stars.