Smartwool PhD Pro Endurance Sock

The Smartwool PhD Pro Endurance Sock is stretchy, comfortable, breathable and with targeted cushioning and designed for the ultrarunner.

Smartwool socks tend to be a popular choice for runners, regardless of the event, distance or conditions. Elite athlete Rob Krar, Western States 100 Endurance Run 2015 winner and 2018 Leadville 100 winner, teamed up with Smartwool to start from scratch to design his perfect trail- and ultra-sock, the PhD® Pro Endurance.

Smartwool PhD Pro Endurance Sock
The Smartwool PhD Pro Endurance Sock was inspired by the desert and comes in limited colors, so limited this is your only option.

The Pro Endurance is designed to be soft, cushioned in all the right places and does not collapse, despite being crew length. The cushioning is specific to the toes/ball of the foot, heel/achilles and protruding ankle bones. As Krar says, “I don’t want the entire bottom of my sock to be cushioned, because I don’t need that cushioning everywhere.”

The design of the sock was inspired by the deserts and canyons where Krar finds peace on his trail runs. Thankfully, the design doesn’t influence the ride of the sock and there are no seams to cause chafing or hot spots. The Pro Endurance is stretchy, breathable and has something called ” Indestructawool™” for added durability.

Material: 57% Merino Wool, 38% Nylon, 4% Elastane, 1% Polyester
Features: Ultra comfortable, great design, seamless.
More Details: Learn more at

Smartwool | PhD® Pro Endurance with Rob Krar



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