Been wearing these for almost 4 years now.  This is my second set after totally wearing out the first, though a couple are still floating around and are serviceable.  I haven't worn cotton socks since getting these and never will again.  Not the best sport wool socks, but the best for the cost.  I'm extremely active, wear all types of shoes in all types of weather, and like good socks should, these disappear once they're on.  They don't slip, they don't bunch, they don't get hot spots, and when they're soaked they don't stretch.  I also wash and dry them with everything else, so that may shorten the life of them, but I'm getting a couple years of daily wear per set.  I also have their lightweight tube socks and their heavyweight, all highly recommended.  I should add, they fight odor fairly well (like wool is known to do).  It's not unusual for me to wear them 2, 3, even 4 days in a row depending on what I'm doing.  They may get a littttle crunchy (gross, I know), but they wear the same and perform the same, still.  Buy several packs and keep them around.