Zojirushi Stainless Steel Vacuum Insulated Mug keeps beverages hot or cold for hours with an easy-to-clean nonstick coated interior, made with a special manufacturing technique to make the body ultra-lightweight and compact. The 2-step lid release process prevents excess condensation on the topper from being flung off while the lid opens and the stopper disassembles for thorough cleaning. Air vent on the mouthpiece allows beverages to flow out smoothly without gushing or overslowing. Safety lock feature prevents the lid from opening accidentally. Bottle has a 1-5/8" (4cm) wide mouth opening. Made of BPA-free plastic and stainless steel. Heat Retention Rating is based on water at a starting temperature of 203°F (95°C) at a room temperature of 68°F (20°C) and Cold Retention Rating is based on water at a starting temperature of 40°F (4°C) at a room temperature of 68°F (20°C)