Smartly built for female runners, PhD Run Ultra Light Micro Socks deliver SmartWool's 4 Degree elite fit system, ReliaWool durability, a virtually seamless toe, and mesh ventilation zones.. . Ultralight cushion: minimal cushioning for maximum next-to-foot performance without added bulk. Overall height: 1.5 in.; narrower profile for perfect women-specific run fit. Blend of merino wool, nylon, and elastane. SmartWool delivers soft, itch-free comfort, even foot temperature, moisture management, and odor control. 4 Degree Elite fit system uses two elastics for greater stretch and recovery to keep the sock in place and improve fit. Fit bands wrap and support the foot for more comfort, faster flex and recovery. ReliaWool technology in high-impact areas provides longer-lasting protection to keep feet comfortable. Mesh ventilation zones designed specifically for female runners provide optimal temperature regulation and moisture management. Virtually seamless toe. Achilles tab. 200-needle construction provides highest-knit density, while maintaining ultralight weight. Knit in the USA of imported yarn.