These adidas by Stella McCartney Ultra Boost knit shoes are ready for day or night with a reflective cage. Featuring the energy return and comfortable cushion of the boost midsole, sidewall support and a sock-like fit. boost 's energy-returning properties keep every step charged with an endless supply of light, fast energy. Knitted textile upper with reflective yarn on heel and toe area. Molded synthetic and mesh midfoot cage. TORSION? SYSTEM for midfoot integrity. Ultra boost tooling; Shiny heel cap. STRETCHWEB rubber outsole is lightweight and elastic, adapting to the ground for stability and working strategically to optimize the unique properties of boost from touchdown to push-off.