First Look: PhD® Pro Endurance Sock by Smartwool

Smartwool PhD® Pro Endurance Print Running Socks, Designed with Rob Krar

Material: 57% Merino Wool, 38% Nylon, 4% Elastane, 1% Polyester
Price: $26
Best Features: Ultra comfortable, great design, seamless.
Room for Improvement: Sizing availability. 

Smartwool socks tend to be at the top of the lineup 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.

The Pro Endurance is 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 malleolus (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.

Here’s a video of Rob Krar talking about the design process. 

These socks are built to last—to take you from 5 miles to 100 and are so comfortable they’re barely noticeable, aside from the style points.