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. 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.