Spill-Proof Technology: The unique straw design features a built-in internal valve that seals automatically to prevent leaks, even when held upside down. Temperature Retention: Built with double-wall vacuum insulation to keep cold beverages chilled for up to 14 to 18 hours. Convenient Maintenance: Both the lid and the stainless steel body are top-rack dishwasher safe. Vehicle Compatibility: The tapered base shape is engineered to fit into most standard car cup holders G352726