Rubber sole fabric-and-synthetic Primeknit textile upper Lace up closure Interchangeable tongue patches Responsive Boost midsole Adidas Expanded Their Boost Collection With The Ultraboost 4.0 Sneaker. Using The Previous Design As A Template, This Version Upgrades The Upper With A Smoother Texture. Released In April 2019, The Upper Consists Of Breathable Primeknit, Caged By A Three-Stripes Midfoot Lacing System. Torsion And Boost Technologies Stabilize And Cushion The Flexible Rubber Outsole For Optimal Natural Movement.