Nike Spark Flyknit brings Flyknit breathability and an anti-fatigue midsole to everyday running and all-day wear. The design focuses on sustained energy through a three-layer midsole and a dual-layer Flyknit upper for breathable support. Key attributes: Gray | Grey | Flyknit | Anti-fatigue three-layer midsole | Breathable upper | Reduced forefoot flexion for sustained energy | Sock-like inner bootie | Heel pillow for added comfort | Durable rubber outsole | Carved-away midsole design | Sculpted collar | Dual-layer Flyknit upper