NIKE Lady Air Relentless 2 Running Shoes Synthetic Mesh upper with synthetic leather overlays - for breathability and support during your training or running or training. TPU midfoot - for superior light-weight support and to give your foot the comfort it needs Full-length Phylon midsole with Nike Zoom - unit in heel for lightweight, durable cushioning when you need it. Rubber outsole with waffle pattern technology - for great traction and amazing durability, gripping your feet to the ground. Flex Grooves - Grooves which enhance grip and traction, giving you a more responsive step.