You've experienced boost™ technology, now with adidas Ultra Boost running shoes you'll experience 20% more for consistent performance and an endless supply of light and fast energy. These shoes also feature a Stretch Web outsole that provides sufficient grip and elastic stretch to help harness your energy without restrictions. The soft, bootie-like fit adds unmatched comfort and a sleek profile.Upper: Engineered PRIMEKNIT mesh with various types of mesh in different areas of the foot provides a forgiving yet snug fit that allows natural expansion of the footExternal heel counter provides optimal heel fit and running comfort. Flat laces reduce irritation. Midsole: BOOST™ offers supreme durability with soft and comfortable touchdown and a smooth transition to the forefoot. TORSION® SYSTEM delivers lightweight arch support that allows the forefoot and rearfoot to move independently for better surface adaptation and stability. Ultralight sockliner adapts to the foot for a custom and comfortable fit. Outsole: Stretch web outsole provides elastic stretch to harness energy without restrictions.