The Stella McCartney x adidas women’s UltraBoost Sandal ‘Black Maroon’ combines breathable comfort with a sustainable build. The British fashion designer’s take on the sneaker-sandal hybrid features a black and maroon knit upper made with Primeblue — recycled high-performance materials that include Parley Ocean Plastic. An open vamp enhances airflow, while synthetic leather overlays and a rigid heel frame provide added support and stability. A full-length Boost midsole is reinforced with a Continental gum rubber outsole.