LD Mountain Centre says:
This is an ultra light ski sock from Smartwool aimed at those skiers who like a very precise fit in their boots for hard charging descents with precision turns. The make up of the sock means that unwanted padding is stripped away allowing the foot to breath and the sock to fit snugly. Even though this Smartwool PHD ski sock is ultra lightweight the merino wool means it still has good thermal properties.
PHD Ski Ultra Light Features:
The PhD® Ski Ultra Light was designed after our classic Ski Ultra Light, except with a 4 Degree™ Elite Fit System and ReliaWool™ Technology to create our most comfortable and durable sock yet.