Pack soup or chili in the morning, and lunch will be steaming when you are ready to eat. Pack smoothies, and it stays cool until lunchtime. This double-walled, vacuum-insulated thermos is leak-proof and airtight. The contents stay hot (for 5 hours) or cold (for 8 hours), while the outer wall stays room temperature and condensation-free. Because it's stainless steel, it's easy to sanitize in the dishwasher. Note: The seal is silicone, but the 12 oz lid and base are plastic (free of BPA/BPS and phthalates).<br><br>Instructions: Pre-heat with very hot water for a few minutes before adding piping hot food, and pre-chill in the freezer for a few minutes (lid off) before adding cold food.