Terrific sock. Well actually both of them. I purchased a couple types of the SmartWool socks. This type and also the SmartWool Hiking Light Crew sock which I bought for my wife, but also fit me. Anyway either are great, but what I particularly like about PHD Outdoor is the slight additional padding on the toes and heal. I primarily wear these with hiking boots, but I also wear them with a low cut pair of hiking shoes which I also wear when riding my mountain bike. Bottom line is that my feet seem to stay the perfect temperature and even though smelly feet have never been my problem, I can often wear these socks for more than a day as as long as three when i need to. Camping, etc. I have also found them easy to hand wash. I put them out to air dry and they are dry a several hours later when I return. I wore them extensively from like Christmas until now, Jan. 17th 2010. During this time I tried wearing a pair of my older cotton athletic socks while wearing hiking boots. By the end of the day they were wearing a blister on my little toe, I could not wait to get them off. I haven't wore my cotton socks since. If you need to travel light you could probably get by with two pair of these SmartWool Crew socks and just keep a them hand washed.