Hydro Flasks are made of high quality 18/8 stainless steel. The bottles have no liner (like most aluminum bottles) and are BPA free. Hydro Flask will keep your beverage of choice at your preferred temperature for hours, whether you choose hot, cold or room temperature liquids. This double wall insulated bottle is lightweight, which makes its great for long hikes, days on the beach, long road trips or everday office use. Even when filled with ice, the exterior of your Hydro Flask will never leave a puddle on your desk, drip on your shirt, or sweat in your bag. Hydro Flask is an product with a Lifetime Warranty! What more could you want in a bottle?