Whether it's bootcamp, tennis or the treadmill, the Nike Flex Trainer 4 training shoes are designed for multidirectional movement and give you a stable, comfortable fit that's ready for any activity. technology injected Phylon midsole offers lightweight cushioning construction synthetic/mesh upper rubber sole details lace up midsole forefoot wrap enhances support and stability multidirectional flex grooves provide improved flexibility rubber pod sole provides extra traction