Contigo AUTOSEAL Astor 2-Pack (Gunmetal) Stainless Steel Travel Mug - Vacuum Insulated Cup Patented AUTOSEAL lid is 100% leak-proof and 100% spill-proof. The AUTOSEAL stainless steel mug automatically seals between sips to ensure no spills. Vacuum-insulated technology keeps beverages hot for 4 hours and cold for 12 hours. Constructed with a double wall and stainless steel inside and out for maximum travel mug performance. Volume: 473mL (16 oz.)