This steel coffee mug is made of food grade, BPA-free and lead-free durable stainless steel. The surface coating can ensure that these outdoor cups with lids are sweat-proof and will not transfer heat. Its sweat-free exterior design prevents your hands from sweating when having cold liquids in it. The strong coffee bottle will not crack or rust. Whether you are working in an office or camping outdoors, your stainless steel insulated bottle will provide a pure, metal-free taste without retaining or changing the flavor.