Iron Flask is Here to Insure You Have the Hydration Needed to Get You Through the Day and Crush it! #yougotthis. Features 18/8 Stainless Steel and is vacuum insulated to keep your tumbler condensation free. The powder coated exterior finish offers durability and an easy grip. Each tumbler is packaged in a color matching gift box. The Rover comes with a 100% leak proof clear flip lid and 2 black straws. The rubber bottom base reduces noise and provides surface protection.