ExOffiio's wool blend BugsAway Hiker Quarter Socks, featuring Insect Shield technology, are the perfect trekking companion for wandering feet. Arch support lessens foot fatigue, and the wool blend yarn and ventilated toes keeps feet fresh, dry, and comfortable. Permethrin, the active ingredient in Insect Shield, is invisible, odorless, and tightly bonded to the fabric fibers, and lasts the expected lifetime of the socks. It repels mosquitoes including those carrying West Nile virus and malaria, ticks, ants, flies, chiggers and midges no see ums. Insect Shield repellent lasts through 70 washings.