With Insulated 18/8 Stainless steel Bottle , heat or cold finds its way inside through the process of convection. THERMOS vacuum insulation creates an airless space between two walls, virtually eliminating the convection process and temperature change. Your drink will stay icy cold or steamy hot no matter what the forecast. Residual liquids, foods, or other contents may become trapped between product components, such as lid parts, container parts, gaskets (flexible band around lid and/or stopper), or straws (if present in the product). Although this product is top-rack dishwasher safe, hand washing is recommended to ensure that all parts of the product are thoroughly cleaned.