Only socks with Cupron Antifungal Fibers have EPA registered fibers that kill 99.9% of Athlete’s foot fungus on the sock after 12 hours of contact. Rejuvenates and improves the appearance and texture of skin. Helps prevent and eliminate odor. Cupron anti-fungal fibers are embedded into the fibers of the sock and will not lose efficacy after 20 washes. FastDry technology wicks sweat. Fights odors.