What is Vacuum Insulation?
Vacuum means the air between the outer and inner layers of stainless steel has been removed to create a vacuum insulation. It blocks heat from transferring through air (conduction). Zojirushi vacuum insulation also features a copper or aluminum layer tightly wrapped around the outside of the inner stainless steel layer. This copper or aluminum layer reflects heat (radiation), further minimizing the temperature change of your drink. Lastly, heat is blocked from escaping through the opening (convection) with a tightly closed lid.