I love these socks to death. I own several pairs and they are the only socks I wear if I have to wear shoes during the summer. They wick sweat well and they keep you blister free. Wonderful.

i'd like to chime in with additional praise for these incredible socks by smartwool. they are comfortable, durable, they dry quickly... i'm sure you can get the gist of their quality from all the rave reviews. the thing that i haven't seen addressed (which should be) is what distinguishes phd from adrenaline and light from ultra light.

the adrenaline socks run slightly more expensive than the phd socks and are constructed of a 70/30 wool-to-nylon mix, whereas phd socks are around 60/40. this allows the phds to 'breathe' slightly better and dry out quicker while possibly sacrificing a bit of softness to the touch. the difference between light and ultra light is simply a marginal decrease in cushioning. i personally roll with the ultra light phds and have never had issues; they're great, even in subfreezing temps! one additional note: for muddy or sandy conditions, consider a taller sock (like mini instead of micro) to keep grit from getting in and rubbing your ankles raw... this is especially important for ultrarunners.

i am a total convert to wool socks for all my running endeavors. hot pavement? icy river? i'll be wearing my smartwool phd micro socks because they simply don't hold moisture, keeping your feet dry and blister-free no matter the conditions.

they are kind of expensive but once you've tried them, you'll never want to go back. some advice: if you are unsure what size to purchase, get the smaller of the two you are considering. it says i should buy large socks for my size 10.5 feet but these are too big and i wind up with some excess fabric bunching up around the heel. the mediums, however, are perfect!

i've owned 2 pairs of ultra-lights and a pair of light ones for 2 weeks, and i haven't worn other socks the whole time (i've washed them of course). i wear them to work unloading trucks, and they keep my feet dry, warm, and i have no sore spots on them. i would easily recommend these socks to anyone i know. actually i already have. i plan on buying more.

These socks are great! They fit right in whether you're hiking a 14er or running laps at the gym. Great breathability. I bought the ultra lights and the lights and these are probably my favorite. I like em light and breathable, and thats what they are.

Love them!!!!!

Light, soft, warm. I was a little hesitant to spent $$ for socks but it was worth it. Short run, long run what ever they perform. No issues with blistering, feet stayed warm in 30* long run. They keep your feet dry and comfortable. Check it out for yourself.

These socks are great at holding back the foot stench. Also I have had a pair for over a year and they still function great. They are very low cut and thus I'm not sure if the thick pad in the back is necessary but I'm not gonna cut if off to see. If you are looking for a great sock that won't give you blisters on long runs, is thin and holds back stink then this is the sock for you.

I really like these socks. They are super breathable, comfy, and padded in the right places without being overly bulky. I'm disappointed by the sizing though. I wear a Men's 9.5 / 10 and according to the size chart that makes me a Large in this sock, but the socks are big. When I pull them on I get that annoying excess heel pouch above my heel because the socks are too long for my foot. Next time I will order a medium.

great socks, I do crossfit and cycle and they work well for both. On a side note I am firefighter as well and they don't get pulled off when taking my boots on/off, big plus. little cheaper would be awesome but, you get what you pay for

As far as fit and function goes these socks are the best. Being a long distance endurance athlete these socks will keep your feet cool, dry, and blister free in the hottest summer days or the coldest winter nights. Take a look at the grey sock version - do you see the little black dashes, well those ensure that the socks don't shift while on your feet. These socks have the perfect amount of cushion and I have used them for a couple of marathons and a Ironman. One cushion step up you will find The PhD Ultra socks, but these have too much padding so I would stick with Ultra Light instead and that is coming from a little bigger endurance boy 5'9 @ 165 lbs. These socks look great in grey and WON'T SURE dirt. Lastly if you are a no-show lover then these are as close to no-show as you get out there. If you JUST BARELY fit into the sock size recommended range then I would size down. I have ordered these socks three separate times from Backcountry.com - each time I have increased my order count. Unfortunately the rest of my old socks just sit in a drawer because I'm not really sure why I would wear anything else. Also as a rare gift giver myself, this is just too good of a gift not to give the people you care about. I have bought dad and the gf a pair.

These socks do a better job of keeping my feet dry than other socks their weight/size, and the wool avoids the stench so I don't have to worry about wearing them all day on a hike or trip and wondering what they'll smell like.

I bought several pairs of these socks last year and whenever I wash them they crumple up really small and I have to stretch them out when I wear them again. They do breathe well so I'll give 'em points for that.