Smartwool PhD Pro Endurance Print Socks

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Size Chart
Bright Blue
Multi Color

We worked with athlete Rob Krar to create the ultimate ultrarun sock. This purpose-built sock features Shred Shield technology to reduce wear from toes, activity-specific minimal and targeted sole cushioning, and an ankle cushion designed for protection on the most rugged trails. These socks were built to go as far as you want to go, with unwavering comfort and performance.


  • Adult Unisex
  • Ultra Light Cushion
  • Crew Height
  • Rob Krar signature sock
  • Indestructawool technology
  • Minimal and targeted sole cushion
  • Achilles heel cushion
  • Ankle cushion for protection
  • 4 Degree elite fit system for a dialed, performance-oriented fit
  • Shred Shield technology reduces wear from toes


57% Merino Wool, 38% Nylon, 4% Elastane, 4% Polyester

Sock Height

Crew Height Sock

Sock Cushion

Light Cushion Sock