Trust the technologically advanced X-SOCKS® MARATHON WMN and prepare for the challenges of long-distance running. In addition to the proven X-BIONIC quality, the optimized features of the X-BIONIC 4.0 generation provide even more comfort and safety for enhanced endurance. The knitting, in which the optimized Air-Conditioning Channel® 4.0 is precisely embedded, promotes highly efficient ventilation. The form-optimized Lambertz-Nicholson Achilles tendon protector 4.0 surrounds the sensitive area above the heel with its two-part padding and protects against pressure, impact, and friction. Along with the Heel Protector, the AirFlow Ankle Pads 4.0 additionally strengthen the protective area around the heel and ankle. The Narrow Arrow construction is specifically tailored to the anatomy of the female foot, and the snug 3-ExpandLadiesStripes fit perfectly to sensitive feet and prevent chafing.