The Sealskinz Thin Ankle Length Sock is ideal for outdoor adventures where minimal insulation is required but with maximum waterproof & breathable protection. Stretch Dry technology incorporates a hydrophilic membrane between two layers of fabric that is totally waterproof, breathable & windproof to protect you in the wettest conditions. It stretches to provide a close, streamlined & comfortable fit. The thin Merino wool lining gives comfort as well as excellent moisture management, & extra padding around the heel cup & instep cushion your stride.A seamless pattern eliminates ridges to reduce rubbing while the elasticated instep holds the sock in place so it doesn't move around inside your shoe.