Perfect fit. Powerful durability. That's what you get when you put on Smartwool Hike Light socks—formerly known as PhD® Outdoor. Featuring Smartwool's top sock technologies, dialed-in fit systems, updated mesh zones, and extended durability zones, they've upgraded these hiking socks to help you push any summit or enjoy any trail in absolute comfort. Light cushioning on the entire bottom of the foot to bring more comfort to your favorite low-cut hiking shoes. And the addition of recycled nylon makes for a more sustainable sock construction. Go farther in ZQ-certified Merino wool hike socks.