Unique lock system integrated in the patented AUTOSEAL system. Slide the button down to lock or up to unlock with only one hand. AUTOSEAL lid is 100% leak-proof and 100% spill-proof. Drinking made easy! Press to sip. Release to seal. The AUTOSEAL stainless steel mug automatically seals between sips to ensure no spills. Grip bottom for added stability in cup holders and on desk tops. Vacuum-insulated technology keeps beverages hot and cold for hours: - 300 ml: 3 h hot – 9 h cold - 470 ml: 5 h hot – 12 h cold - 600 ml: 7 h hot – 20 h cold Fits most standard car cup holders.