Pedag Keep Warm 2 Pair Pack: Save a little when you buy the 2 pair pack. 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, the bottom layer is hard wearing brown wool felt. 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. Wool, Cork and Felt Layers.