The adidas Ultra Boost was first released in 2015 and quickly became one of the most popular running models from adidas. The versatile colorway of the Ultra Boost 4. 0 sports a grey Primeknit upper and a matching heel cup with tonal branding, while contrasting color makes a statement on the TPU Three Stripes cage in bright green. The sock-like upper sits atop a white Boost midsole and black Continental rubber outsole to create superior comfort and flexibility for the foot. | UltraBOOST Grey Two.