When you’re playing sports, running, weight-training, or doing any other physical activities, 100% cotton socks are not the best option. Socks manufactured with polyester and mesh wick sweat from the feet, breathe better, and weigh less (excluding ones like these). They last longer too. My sock drawer is filled with Finish Line Performance Socks. To be in compliance with AR 670-1 as a Soldier, I would wear Finish Line cotton-polyester blend socks.