In true purist fashion and in response to popular demand, the Ultra Pure features the lightweight and breathable design of the Ultra's single unit cage but now without the removable sock. The 3D upper-outsole combines a perforated upper and a dual density, high-abrasion, hex-flex outsole in a single unit. Like all VIVOBAREFOOT shoes, the anatomic toe box of the Ultra provides plenty of room for the toes to splay and the foot to move naturally. For a personalized fit, the elastic cord and lock-lacing system fasten quickly and securely. You can take these shoes for a run in the mud, a splash in the sea or stroll down the street; wherever you go, the Ultra Pure provides maximum proprioception for the ultimate barefoot experience.