adidas Running just rolled out the next generation of the Ultra Boost. The Ultra Boost 4.0 has landed on adidas.com in Grey. The UB 3.0 is extremely comfortable, so it’s only right to wonder what does the UB 4.0 have to offer. How does the Primeknit differ from 3.0? Depending on how curious you are, you can find out now by clicking here. Does the Ultra Boost still interest you? Are you curious about the UB 4.0?