Tulip Slippers By Ilse Jacobsen Hornbæk. The Upper Is Made Of Recyled Microfiber Attached To Our Iconic Tulip Sole, Made Of 75% Natural Rubber And 25% Recycled Rubber, With Match Colored Recycled Thread, Using No Glue. The Slippers Are Lined With Soft Faux Fur Consisting Of 100% Polyester. The Insole, Lined With Pig Suede, Has Padding And Support, Ensuring Great Comfort.