adidas Performance Men's Ultra Boost Street Running Shoe 100% Textile/Synthetic Imported Rubber sole Weight: 12.2 ounces (size 9); Runner type: stable; Stack height: 32 mm / 24 mm (8 mm differential) adidas Primeknit is carefully engineered to naturally expand with your foot while you run to give you a more comfortable fit and help reduce irritation boost's energy-returning properties keep every step charged with an endless supply of light, fast energy 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 TORSION SYSTEM for midfoot integrity; Ergonomic heel structure for added support; Continental Rubber outsole for extraordinary grip in wet and dry conditions;