Natural wool is a modern high-quality, environmentally friendly insulation for winter boots. Natural wool is very durable so the lining will not wear out. These boots are stand-in-a-bathtub waterproof but the inside may feel damp after a long day due to sweat. Don't worry, the wool doesn't require any special care. The lining will dry in 8-10 hours in a warm, heated room, and every morning your boots will be dry.