Made from 100% merino wool, the Castelli wool socks are the ideal choice for long winter rides in cold and windy conditions. With its softness, merino wool keeps your feet warm and comfortable while letting moisture evaporate. This breathability is especially important for cyclists, as winter months often mean cramming socks into shoes and shoes into booties. Without a means by which moisture can escape, your feet become colder faster. Wool socks are an important cold-weather companion.