The BIRKENSTOCK Zermatt is our first true slipper. It features our iconic cork latex footbed, and to keep you extra cozy, it&';s fully lined in genuine shearling that will keep your feet warm all winter long. The upper consists of soft genuine wool. Anatomically shaped cork/latex footbed lined with shearling Upper: wool felt Footbed lining: shearling Sole: latex Details: Decorative stitching "Made in Portugal" Materials Upper material: Wool felt Wool felt counts among the oldest textile materials in the world and is the typical upper material for slippers. Insole: Shearling Shearling is high-quality, soft sheep- or lambskin. The material is warm, breathable and has temperature-regulating properties. Footbed material: Cork Cork is a sustainable material extracted from the bark layer of the cork oak. This natural product is insulating and offers very good cushioning.