Use for multiple day climbs and expeditions to protect your thermal socks from becoming soaked with sweat. .5 oz Urethane coated 70 d nylon taffeta VB's take up little room and can be worn between a liner sock and your favorite trekking or expedtion sock with either single or double boots. Elastic gather at ankle and sealed off above boot top by elastic cord and posi-grip cord lock. Try some strong antiperspirant or foot powder to further control sweat and increase comfort. Also take along few pre-packed moistened towelettes to clean and freshen your feet at the end of the day - a real treat. Comes in micro stuff sack.