It is an extremely high-quality and sophisticated shoe with the latest technology. The heart of the Ultraboost is the Boost outsole, which guarantees maximum energy return. This saves you energy and allows you to run even further and faster. The Tailored Fibre Placement, a sewn-on reinforcement, gives your foot stability and the sock-like fit adapts to your foot and is particularly easy to put on and take off. With the Ultraboost 21 you optimize your training and competition and get a breathable shoe in a modern, stylish design.