The STRIDE is a new technical midweight sock offering which is the update to the RUNNING II. The needle count has increased to 168 to offer a cleaner look, a softer hand and a more performance fit. Wrightsock patented Double Layer reduces the causes leading to blisters - friction, moisture, and heat - with and integrated system of two socks knit together. Sizing (All US sizing): Small- Womens 4-6, Mens (NA). Medium- Womens 6.5-9, Mens 5-8. Large- Womens 9.5-11, Mens 8.5-11.5. X-Large- Womens (NA), Mens 12-14.