There is absolutely no vacuum leaking vacuum seal, you can throw it into your child's sports bag or backpack for outdoor hiking, or take it to a yoga class, or take it to work without worrying about leaks. Easy to carry, leak-proof, no spills, no sweat - carry your trusted drinks with you. The coffee thermos can be easily slipped into the car cup holder, bike rack or backpack. Keep an appropriate amount of liquid. The perfect mouth opening makes drinking comfortable. Vacuum insulation designed for maximum temperature retention; keep liquid hot for 5 hours, cool for 9 hours.