Nike Pro Hyperwarm Hood Thermal Fabric: Nike Therma-FIT Technology Helps Manage Your Body Heat To Keep You Warm In Cold Conditions. Flat Seams: Flat Seams Feel Smooth Against Your Skin, Reducing Irritation During Wear. Versatile Design: Form-Fitting Design Can Be Worn On Its Own Or Under A Helmet, And It's Convertible To A Neck Gaiter For Custom Warmth. Stretchy And Lightweight: Designed For Optimal Flexibility, This Hood Provides A Snug Fit Without Restricting Movement.