The Double Wall Vacuum Cups are made from high-quality 304 18/8 food-grade stainless steel, offering excellent heat and cold insulation while being BPA-free, rust-resistant, and durable. These stainless steel cups are designed to prevent scalding and maintain the temperature of your drinks, making them safe and long-lasting. Ideal for all occasions, they are perfect for both adults and children, especially for outdoor activities like camping, hiking, and picnics, where their ability to keep drinks chilled for longer makes them a great choice for outdoor entertaining.