; The HFS runs small. We recommend choosing 1/2 size larger than your usual size. The Xero Shoes HFS running shoe offers a sure-footed connection to the ground that keeps you stable and agile on the road. This design offers a tire tread-inspired sole, soft moisture wicking lining, and a wide toe box let your feet move naturally. XERO-drop zero drop design allows for proper posture. 5.5 mm FeelTrue rubber sole to protect your feed and give ground-feedback. Removable 2mm insole for a closer-to-barefoot experience. Wide toe box so your feet may naturally splay. No animal products used in the production of this shoe. Polyester upper and lining. Man-made footbed and outsole. Imported.