NIKE Men's Celso Motion Slide Sandal Black/White Synthetic UPPER: Neoprene-like strap features seamless comfort and a dynamic fit. With design cues that mirror the Nike Free Run 3. MIDSOLE: Dual-durometer midsole/outsole features a soft, pliable Nike Solarsoft foam midsole with built-in grooves for optimal airflow. OUTSOLE: Nike Solarsoft foam in a harder durometer for durable traction and stability. Deep flex grooves that mimic Nike Free tooling.