Boys' Nike Infant & Toddler Flex Runner 4 Running Shoes The Nike Flex Runner 4 is made for little movers who are always on the go. With an easy slip-on design, these sneakers deliver a snug fit without the hassle of laces—perfect for busy mornings and wiggly feet. Lightweight and flexible, the cushy foam sole supports natural movement while soft materials keep every step cozy. Bold Nike branding adds sporty style to this everyday essential for infants learning to explore their world.