Pedag Keep Warm: All natural materials combine for effective, breathable, cozy warmth. Keep Warm's top layer is 100% pure, quilted unbleached wool, the middle layer is natural insulating cork and the bottom layer is hard wearing brown wool felt. Keep Warm is thin and great for winter boots, comfort shoes and slippers. Keep Warm is approximately 5 millimeters thick (approximately 0.2 inches) depending on the size. Made in Germany.