NIKE Mens Dual Fusion ST 2 Running Shoe Blue/White Mesh upper for breathability and a comfortable fit Internal midfoot strap that runs from the midsole up to the laces for a snug, secure fit Dual-density Phylon foam with soft foam in the center and firm foam at the perimeter for plush, supportive cushioning Flex grooves at the midsole and outsole for enhanced flexibility and natural range of motion Inner sleeve for a soft, comfortable fit