This is an attractive, stainless-steel travel mug with a sleek, modern design. When I put hot water at approximately 140° temperature into this thermos mug, it stayed hot for approximately 3-4 hours. Cold drinks stayed cold about 2 hours. The lid of this travel mug is so unusual in its construction that I could not figure it out without my husband's help. There is a small silicone bar on the top of the upper silicone portion of the black, plastic lid. When you shove it forward, the lid is closed and leak proof. When you shove it backwards, the top portion of the lid tilts slightly upward, about 20°, to allow liquid to be poured out into a glass or mug, or to be tipped into the mouth. There is a huge problem with this design. If you take off the lid, you will discover that there is no access for cleaning the area that is underneath the tiltable, upper part of the lid. There is a small, inaccessible compartment there which can become a hotbed for retaining food particles and growing toxic mold, because there is no possibility for reaching any kind of implement, even a tiny, straw-cleaning brush, inside that area and cleaning it. The only way to stop a build-up of rotting food particles and mold--and there is no guarantee it would even work--might be to soak the lid in diluted vinegar or hydrogen peroxide on a daily basis. Which of course, would be a huge hassle and, over time, with very likely damage the lid by eating away at its finish. If you opt to wash this travel thermos in the dishwasher, in hopes that the hard swish of hot water will solve the problem of the lid, you will have a potential issue of water getting trapped up inside the lid. Which means you will have to shake it out thoroughly, and even so, not be guaranteed that you won't be growing mold inside the lid. The dishwasher may not be able to remove all the food particles within the lid from coffee or tea or any creamer products or sweeteners that you might have put in your coffee or tea. If you choose to purchase this product, for the above reasons, I would not recommend putting anything in this mug except water and never putting it to your lips and drinking out of it. Drinking from it will impart saliva to that uncleanable portion of the lid, and that too can cause mold buildup. For me, this design flaw is a problem of the manufacturer choosing a sleek appearance over hygienic functionality, resulting in a major product failure.
