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Unless you're an anomaly, your feet will sweat during activity, so the SmartWool PhD Outdoor Ultra Light Micro Socks are designed to breathe and offer cooling, quick-drying comfort no matter how rigorous your favorite outdoor activity can get.

  • Blended composition maximizes the benefits of each separate material while minimizing fabric drawbacks
  • Soft, merino wool breathes well, helps regulate body temperature, and is naturally odor resistant
  • Nylon components dry quickly, breathe well, and add extra durability
  • 4Degree Elite Fit system employs ankle, instep, and arch elastic bands for a snug fit, support, and circulation
  • ReliaWool tech on the bottom of the sock combines high-density impact zones along the ball and heel for long-lasting protection
  • Virtually seamless toe construction limits irritation and chafing

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Here's what others have to say...


Bought 3 pairs, Love em.

  • Familiarity:I've put it through the wringer
  • Fit:True to size

I have had these socks before, and they are great. They are nice, thin, and lightweight, perfect for the hot summer months. They breathe well, and don't get sweaty and soggy like standard cotton socks. These are probably my favorite sock that Smartwool offers.


My go to trail running sock.

  • Familiarity:I've put it through the wringer
  • Fit:Runs small

I wear a minimalist trail running shoe, so having a super thin and lightweight sock is key.

I exclusively wear these when trail running during the summer.

They're not the best for casual use, probably too thin.


Amazing comfort and feel

  • Familiarity:I've put it through the wringer
  • Fit:True to size

I think it is fair to say there is a lot of skepticism that goes around when it comes to "high tech" socks. Most people just think "socks are socks".......Most people are very wrong my friends. Wicks moisture super fast. Does not over heat the feet on extremely hot days. You can use them multiple time with out washing them thanks to the marino fabric and anti-order propers that are naturally found in marino wool, and the fit that is gives you foot is optimal. Just try one pair, what have you got to loose? You can always return them right?


Excellent sock for the price.

  • Familiarity:I've put it through the wringer
  • Fit:Runs small

Great running sock. Ultra light weight, durable, long lasting, breaths and keeps its shape. Wash, spin, hang to dry. Very easy to maintain. If in doubt of size, go one size larger.


Ultra light weight!

    These socks are very minimal. Very short on the ankle and very thin material. I assume these would be great for running, I however am not a runner so I ended up returning these. If you are looking for a thin light running sock this is a good one.


    The real thing...

      I initially got into Smartwool socks when I started trail running. I wanted to make sure I had good foot care and a solid wicking fabric on my feet for those long trail runs. Smartwool did the trick!

      I now use these socks for both road and trail running as well as just everyday use. They are cool/warm dry and comfortable. I own about 6 pairs at this point and will continue to grab some when they pop up on sale! ;-)

      The fit around the toes and ankle are very comfortable. I'll put these to extreme use this summer in a summer trail ultra and we'll see if I can stand by this review after that. My guess is "Yes, definitely".