Never worn , Vionic Women's Kirra Backstrap Sandal Natural Snake Size 8.5 No Box Leather upper. Footbed: microfiber wrapped EVA absorbs shock, reducing stress on feet, ankles and knees. Durable rubber outsole with a patterned tread provides traction on a variety of surfaces. Orthaheel Technology is biomechanically designed to hug your arches and support your feet in comfort. Vionic sandals' built-in orthotic is shown to be effective in helping to treat heel pain. Adjustable ankle strap.