Great for 5K's and 10K's!
Using these for my running events. Great socks! Compared to typical socks, these are lightweight and seem to soak up moisture while letting my feet air out. It's nice to finish an event and remove your shoes without having soaked feet! I have probably around 20 pair of Smartwool socks and they are the best quality by far! Will definitely by more!

A great sock for the trails
Smartwool makes the best socks, period. The PhD line is the best of the best. The fit is perfect. The cushioning is just right. The comfort is superb. The quality is top-notch. I'm continually amazed at just how good a merino wool sock feels on my foot when I am running in the summer here in Southern California. If you like wool socks for running then you will like this. If you are skeptical about wool socks then give this one a try, you won't be disappointed. I like this sock especially for trail running because the cuff goes above the ankle. This is useful for keeping trail debris out. A note about the fit: this sock has a lot of stretch so make sure to slip it on instead of pulling it on. I wear a size 9.5 shoe and I ordered the large. The fit is perfect. These socks really are worth the money!

Last forever!
It's great to find a sock which feels comfortable out of the package, but generally after a few washes the material feels thinner and thinner. With Smartwool I've washed a ridiculous number of times and can barely tell these aren't new anymore. I own both the short version and these. I prefer the ankle on the these so that there's something to grab onto when adjusting. The super short version may cut a few oz from the weight, but i'm not sold.

Great cycling socks
An excellent summer cycling sock. They don't stretch in use and bunch up under your foot. No special care needed. They go right in the washer and dryer with my other cycling clothes.

best sock!
i order 4 different pair of higher end athletic socks from Altrec, these are my favorite. will order XL next time as i'm an 11 and the L is a little tight, but once worn, feel great and warm. worn all day too, very comfortable, will be ordering more