Nike Ja Fly 4 Track and Field Sprinting Spikes Finish through the tape 1st in the Nike Ja Fly 4, a sprint spike made to help you set personal records in everything from the 60 to 400 meters. Our lightest Nike Sprint spike sports a revamped plate for enhanced stiffness and an updated upper for better breathability, so you can stay focused on doing your best. Lighter, Faster An updated woven upper gives you security and containment at a significantly lighter weight than the Ja Fly 3, but with more breathability. Explode Out of the Blocks A completely new plate using computationally designed hexagons delivers stiffness in key areas to help you fly off the starting line and maintain speed throughout the race. Lace Up The Nike Racing shoelace is lightweight with notches and just a little stretch that allows for a secure fit that stays tied in all conditions. Sizes shown for Unisex shoes are in Men’s US, Women’s equivalent are 1.5 larger e.g Men’s US 8 equals Women’s US 9.5.