The 58 degrees Onyx Cool Cap is made with a specially formulated plant-based cooling phase material (PCM) that safely and comfortably fits inside a construction hard hat or baseball cap to cool your head and protect against heat stress. Provides soothing relief for headaches and migraines. May also be used to stimulate hair growth. This cool (not too cold) cap is safe to wear directly on the skin without risk of ice burn or frostbite. Maintains constant 58 degrees cooling for 30-45 minutes, depending on use. Re-cools in the refrigerator in 30 minutes or in a cooler of ice. Latex-free and made in the USA! To clean, wash with mild soap and water then air dry.