Mile after mile, NANOspikes footwear traction provides unrivaled comfort, grip and performance when running on icy streets, roads and sidewalks. Ten extremely wear-resistant tungsten carbide spikes per foot bite into frozen surfaces and highly durable dual-compound TPU traction plates feature specialized inserts that disburse impact forces. NANOspikes also allow users to safely transition between dry and slippery pavement without affecting the natural running motion, providing the high performance road runners demand so they can train and stay outside all year round. US Men's Shoe Size:5-6.5 = XSmall, 6.5-8 = Small, 8-10 = Medium, 10-12 = Large, 12-14 = XLarge Us Women's Shoe Size:6-7.5 = XSmall, 7.5-9 = Small, 9-11 = Medium, 11-13 = Large, 13+ = XLarge European Shoe Sizes:36-38 = XSmall, 38-40 = Small, 40-43 = Medium, 43-45 = Large, 45-48 = XLarge