Extra low in the leg for protection from the element during activities where minimal insulation and maximum breathability are required sealskinz 100 waterproof thin ankle length socks are british designed and manufactured to be totally water resistant fully breathable and windproof while remaining flexible and stretchable for great fit and performancethese sealskinz socklets have a hydrophilic membrane outer with a merino wool lining blocking water out while allowing sweat to escape