Casual flat. IFLEX soles are made of Thermo Plastic Rubber, an indoor/outdoor material that is waterproof as well as non-marking. This innovative material enables the shoe to bend up to 90 degrees. In addition, the outsole provides a slip-resistant surface that is both soft and durable, delivering the perfect marriage of fashion, fit and function. Nubuck or manmade upper; mouse over your color choice for upper information. Man-made lining and sole.