The Iron Flask® Rover 2.0 Tumbler brings everything you love from the original Rover and adds a 100% leakproof design with both the flip lid and straw lid included, plus a rubber bottom for extra protection (and less noise). Every Iron Flask® tumbler cup is vacuum-insulated between two walls of the highest-quality stainless steel, giving you durability, reusability, and temperature control you couldn't dream of with a plastic tumbler cup. Meaning you can expect 20 hours of coldness or five hours of hotness for your drink of choice.