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Run smarter not harder.

The Smartwool Women's PhD Run Ultra Light Micro Sock has just enough sock at the ankle to shield you from cuff on ankle rub but is still lightweight enough to keep you light on your feet. In addition to the the natural breathability of merino wool, mesh ventilation zones promote further ventilation, so you never feel the sweats in your feets. 

  • Merino wool, nylon, elastane blend
  • Reliawool technology
  • Mesh ventilation zones
  • Ultralight weight

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Here's what others have to say...


Great socks!

  • Familiarity:I've used it several times
  • Fit:True to size

I love these socks with my Keen Whisper Sandals. They are thin enough that they fit great with the Keens, but also keep my feet warm and dry. My feet don't sweat in them, and when I walked in water they didn't get soggy on my feet. I also wear them with my sneakers when I go to the gym. I ended up buying 3 pairs of these because I like them so much. I machine wash them in cold and hang dry them. I wear a size 6 shoe and the Small size fits really well. I ended up buying a pair of the men's for my husband and he loves them too!


Great socks for multiple activities

  • Familiarity:I've used it once or twice and have initial impressions
  • Fit:True to size
  • Height: 5'5"
    Size Purchased: Small

I bought these socks for a long distance bike trip I'll be going on this winter in New Zealand (so it will be summer there). They have great arch support with slight compression across the top of the foot to the arch. The heel also has some extra material to add some protection against rubbing against your sneaker. They are lightweight however and do not protect against biking in the high desert on a 40 degree day. They should be absolutely perfect for a 70 degree in New Zealand where rain is always a factor. SmartWool is always a great go-to product for warmth when wet and lack of smell. One tough training ride down and I'll won't have to wash them before the next one.


Surprisingly Warm Socks

  • Familiarity:I've used it several times
  • Fit:True to size
  • Height: 5'6"
    Weight: 140 lbs
    Size Purchased: Medium

I actually ordered these because I needed to spend a little more to qualify for free shipping on something else I bought. I regularly wear the Smart Wool cabled crew length socks which I love, so I didn't hesitate ordering these.
These footies/socks are quite thin so I was initially concerned that they might not keep my feet warm. In fact they do just as good a job as keeping my feet warm AND dry as my thicker SmartWool socks.

They run true to size and they're nice in that they're almost invisible with sporty shoes on.


Super socks

  • Fit:True to size

I'm very happy with these! They're thin but not wimpy. Slide easily into my shoes. High quality socks and excellent fit! I want 5 more pairs.


Cool Socks!

  • Familiarity:I've used it several times
  • Fit:True to size

These socks are wonderful! Lightweight and breathable, even in hot and humid North Carolina summers!


Brilliant long lasting sock

  • Familiarity:I've put it through the wringer
  • Fit:True to size
  • Height: 5'2"
    Size Purchased: Small

I have purchased these in the past and had to get some more. They are great for using in your tenny's. My feet swell at any hint of heat and especially if I'm moving so these socks are great as they are thin enough to allow for swelling and they wick and keep my feet dry! I love the tab on the back - which helps prevent possible blister prone people/or the shoe that might give a blister because of where it sits on your heel. My last pair I had for about 3 years, and even then they were still functioning. I didn't have holes, and maybe by the end of my exchanging out the heel was a tiny tiny tiny bit thinned, but not really. They were still usable. I highly recommend these and think these are worth the investment. Well made and this season has great colors which I as a color lover really really like.