Only socks with cupron antifungal fibers have epa registered fibers that kill 99.9 percent 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. Fast dry technology wicks sweat. Fights odors.