The sealskinz road thin hydrostop mid socks are fully breathable waterproof and windproof they have a merino wool lining which ensures the sock wicks away sweat to keep feet dry in high intensity activities features stretchdry membrane waterproof windproof and breathable hydrostop cuffs an elastic insert and silicone cuffs ensure a close fit that prevents water from entering through the top merino wool lining fine natural fibres that offer an excellent wicking performance calf high