Nivia Track and Field-400 spikes have a breathable mesh upper to keep your feet cool and comfortable, with a lightweight TPU stitchless upper when the pace heats up. Asymmetrical lace design for snug fit, supportive TPU sole plate. TPU fusion technology in a hexagonal breathable mesh upper for long-lasting comfort. It creates a better, healthier environment for your feet to thrive in. The fusion technology construction produces an irritation-free fit, reducing bulk, layers, and weight for high breathable hexagonal breathable mesh is light in weight and allows you to move quickly. Two layers of high-density foam line the collar and mould to the athlete's foot to create a personalized heel fit, adding soft support and custom comfort. The soft cushion NR EVA inner insole improves cushioning and comfort.