Dual purpose is what glerups Wool Boot Rubber serves, allowing you keep your feet toasty warm indoors and walk outdoors to check the mail. It has a great capacity of absorbing moisture, while keeping your feet warm and dry. Wool upper, lining, and insole. Many people use wool to keep warm, but in fact wool can also help keep the body cool. That's because wool absorbs moisture without feeling damp, up to 70% by weight by the way! - This significantly outperforms synthetic fibers or cotton. It is particularly advantageous in the summer when it is hot outside. This way no matter how much you perspire you can stay feeling dry and temperature regulated. Rubber outsole.