Heeled Ankle Rubber Boots By Ilse Jacobsen Hornbæk. Decorated With A Diamond Textured Mudguard And A Decorative D-Ring At Center Back. These Wellingtons Are Made Of Sustainably Harvested Natural Rubber And Have Been Cut By Hand. The Material Can Withstand Temperatures Down To -20° Celsius. The Rubber Composition Is 80% Natural Rubber And 20% Secret Formula. Entirely Pvc-Free, Our Boots Contain No Animal By-Products. If Not Treated Regularly, Natural Rubber Will Develop A White Surface Over The Years. This Is Simply Because In Time The Rubber Slowly Lose Its Essential Oil. To Keep Your Boots In Great Condition For Many Years To Come, We Recommend That You Treat Them Once A Month With Our Oil.