When Ariat says these are Heavyweight Performance Merino Wool Blend Crew Socks, they mean it. Unlike some other inchmerino wool blends inch, the majority of these socks is merino wool yarn. So you can reap more of its benefits, like natural antimicrobial and moisture-wicking properties. Plus, these socks are nylon plaited with 144 needle construction for super durability. And though heavyweight, the ventilation panels ensure sufficient airflow to keep you from overheating. All with full cushioning for total, all-over comfort. 77/21/2 merino wool/nylon/LYCRA spandex for comfort with just enough stretch Full cushioning from top to toe for all-over comfort and maximum impact absorption Ventilation panels and top of foot to keep temperature perfect Seamless toe for smooth wear Arch support helps lessen fatigue Nylon plaiting with 144 needle construction ensures durability Crew height Unisex sizingSizing Detail: Medium fits Men's shoe size 5-9, Women's shoe size 6-10 Large fits Men's shoe size 9-12, Women's shoe size 10-12 Extra Large fit Men's shoe size 12-14.5 Order today!