The high-performance X-SOCKS RUN RETINA 4.0 are just right for your long-distance runs. The Retina Ultra-High Definition technology makes these socks lighter and more comfortable. The newly designed AirConditioning Channel 4.0 allows air to circulate along the soles of the feet and effectively cools them. At the same time, the newly designed Lambertz-Nicholson Achilles tendon protector 4.0 protects the sensitive tendon area through dual cushioning against pressure, impacts, and friction. Additional protection in the heel and ankle area is provided by the AirFlow Ankle Pads. Airconditioning Channel 4.0: 3D structures and specialized technical yarn improve air circulation and thus foot ventilation.