Under Armour Women's Heatgear Volleyball Serve Socks The Under Armour Women's Heatgear Volleyball Serve Socks also feature ArmourBlock technology to prevent growth of odor-causing bacteria in the sock, as well as convenient foot swipe zones, a must-have for volleyball players to keep their shoes clean on the court. 86% Olefin / 12% Nylon / 2% Spandex.