The Naot Rianna in Oily Coal Nubuck are comfortable, podiatrist-approved women's sandals known for their supportive fit and elegant design. The "Oily Coal" color is a shade of black. The sandals feature Naot's signature anatomic cork and latex footbed, which is wrapped in pampering suede and designed to mold to the shape of your foot over time. These footbeds offer arch support and help relieve pressure. Adjustable Fit: The design includes one band and cross-instep straps with a faux buckle, but actually uses a hook-and-loop (Velcro) closure for easy on and off and adjustability. The fit is generally considered narrow to medium width. Design: Part of the "Flat Elegant Collection", the Rianna is a flat sandal with a 0.75-inch TPR (thermoplastic rubber) sole. It has a padded upper and heel cup for enhanced comfort. Style: The simple, strappy design makes it a versatile sandal that can be dressed up or down for various occasions.