EXTREMELY LIGHT, EXTREMELY CONVINCING: BEST IN TEST TIMES TWO. The sun and pleasant temperatures convince us quickly to head out on an ambitious adventure. But the foot that sits snugly in a shoe warms up and starts to sweat. The X-SOCKS® Extreme optimally transports warmth and moisture away. Special features: The AirGuide™ functions as a spacer and is placed along the AirConditioning Channel® to facilitate continual air circulation. The patented AirCool Stripes™ under the soles also allow temperature-regulating fresh air to circulate. Manufactured with a light touch but still technically perfect, it creates a typical X-SOCKS® “bare foot“ environment.