Smartwool Women's PhD Outdoor Light Micro Socks The PhD Outdoor Light micro is made for the trail. Featuring Indestructawool technology for ultimate durability, we've designed this sock to outlast your greatest adventures. And with features like mesh zones for maximum breathability, a Virtually Seamless toe and the power of Merino, they'll help keep you comfortable every step of the way. A micro height barely shows above low trail shoes while the women's-specific fit provides an overall slimmer fit and narrower heel. Smartwool Women's PhD Outdoor Light Micro Socks