SixSox are Infused with Ionic+™ (XT2®) Silver Yarn Technology that ensures Added Comfort, Odor Protection & Better Hygiene while also being Eco-Friendly! Inspired by the US Military, the US Military was a pioneer in Antimicrobial clothing. At SixSox, they use the same supplier of Antimicrobial Silver Yarn. Made by an American company called Noble Biomaterials. Ionic+™ (XT2®) Silver Yarn is regarded as an industry leader & one of the world's most innovative materials.