Using insights from runners like you, we prioritized functionality in this slim-fitting running vest. Its sleek, reflective material combines with lightweight synthetic insulation and our heat-regulating tech to help you stay warm mile after mile. Benefits:Nike Therma-FIT ADV technology combines heat-regulating fabric with advanced engineering and features to help keep you warm in cold-weather conditions. Synthetic fill helps keep you insulated and warm. Zippered side pockets work with a pocket at the lower back to provide secure storage for your essentials. [] Product Details:Body/Lining/Fill:100% polyester. Reflective details. Whistle at collar. Locker loop at back neck. Do not wash. Imported. Not intended for use as Personal Protective Equipment (PPE). Style: HV2762; Color: Vast Grey/Black; Size: XS; Gender: Female; Age Group: Adult | Nike Swift Women's Therma-FIT ADV Reflective Running Vest in Grey, Size: XS | HV2762-078