THERMOS 16 Ounce Vacuum Insulated Stainless Steel Travel Tumbler

I can't think of any way to improve on this design. It meets every one of my requirements. Keeps hot liquids, primarily coffee, hot for hours, well beyond the time I need. It also does the same for cold liquids. It is truly leak proof. Turn it upside down and nothing. It is sleek. Very hot liquid inside, no feeling it on the outside. Easy to clean. It does not retain the coffee taste in the vessel, so you can easily move to another liquid without tainting the taste.As for the top, which is the key to the temperature retention, I ended up buying a second top ($3 plus shipping) just to have a backup. But I find myself using one top for coffee and the other for cold liquids. This way, there won't be a residual coffee taste when shifting between liquids. I'm not saying this would be the case, but it enables me to avoid the need to clean the top each day. I do rinse it, and maybe once a week I take it apart (very easy) and clean the four components.I have another type of thermal container that is leak proof that I use for cold liquids when, primarily, going for a bicycle ride. Leak proof is the key because I put it in the bag on the front of the bike. It is not intended to be used for hot liquids since it has a narrow spout and wouldn't be an appropriate way to drink anything but cold liquids. Now, with this Sipp, I have another leak proof, highly thermal way to carry cold liquids on bicycle trips. Having two containers worked out very well for my most recent hot-weather trip. And the liquid flowing from the Sipp is more like drinking from a glass rather than a narrow spout.Prior to the Sipp I was using an older version of Thermos that has a top that is not leak proof but rather, you lift a small plastic cover where the liquid will come from, then snap it back after you drink a sip. This has served me well for many, many years. I don't know when the Sipp was first introduced, but had I known about it then, I would have benefited by buying it even sooner. It's that much better than what I was using.I love discovering great products that rise above expectations. Every once in a while I find such a product. This is one of them.Update:I just wrote this review about 4 hours ago, prior to my visit to get my semi-annual blood work done. What I found out about my Sipp is that much more exciting and revealing.Here's the scenario. Our coffee machine went off at 5:20 a.m., ready by 5:30 a.m. I went to pour the coffee, a mug for my wife, my Sipp for me, at 5:30 a.m. Since I was fasting prior to my scheduled 7:30 a.m. visit to get the blood work, I could only hope that a little over two hours from when I put the coffee in the Sipp that it would still be hot enough for my full enjoyment. I arrived at Quest, the blood work facility, at 7:35 a.m. It was crowded this time, but I never thought it would take an hour until my turn. Meanwhile, I'm suffering from coffee deprivation all the time, fully anticipating the Sipp that was waiting for me in the car. It was fully a little over 3 hours before I was finished with the blood work and could now break the fast with "the best part of waking up." All the while I was sitting in the waiting room I was thinking how, maybe, the Sipp would not quite keep the coffee hot but rather would only give me a somewhat lukewarm reception. Well I'll be. It was hot! After 3 hours sitting in my Sipp. My contingency plan to stop at the local Wawa to get a hot cup of coffee if my Sipp coffee wasn't up to snuff was rendered moot. Wow! I just love this Sipp. It's now 9:15 a.m. - 3 hours and 45 minutes after I poured the coffee into the Sipp, and I'm still drinking it...hot.By the way, I just love great products that perform. And I don't work for the company.

I bought this Thermos tumbler to replace a perpetually leaky travel mug that dumped coffee on me one too many times before law school, and I could not be happier with this tumbler. I can turn this tumbler upside down and not leak any coffee. The thermally insulating properties are second to none -- I can fill it with hot coffee at 6:30 a.m. and by 2 p.m. my coffee is still warm. At least it would be if I didn't drink it so quickly. I would not be surprised if you couldn't fill the inside with actual fire and the outside would still be cool to the touch.The tapered design allows it to fit comfortably into any cup-holder and fits both large and small hands, almost as if the tumbler itself changed size to the requirements of the bearer. The ring shape also is conducive to both right-handed and left-handed travellers. Coffee flows freely and doesn't sputter or leak. The stopper is a push-button that clicks open and closed. Peculiarly, the stopper has a red "danger" line that shows when the stopper is closed rather than open. I'd have thought a red line would mean "Caution: hot coffee may flow and burn you," but the instead it only shows when closed. A quick mental rearranging just has me associate red with "Coffee will not flow: Danger to you and everyone else!" Somehow this seems more prescient. My only complaint is that the stopper itself is very click-y and is a little too audible to click in class more than once.Curiously, my tumbler did not bear the "THERMOS" mark that appears on the product picture. I thought for a moment I saw it appear when I put particularly hot coffee in it, but it may have just been a trick on my bleary morning eyes. The brushed steel is very attractive and quite sturdy. It's held up a to a few accidental drops (without busting open) and only a small dent to show for it, leading me to think that the tumbler must be forged from titanium or mithril or something other than steel.I look forward to seeing how this tumbler holds up against the rigors of law school, and I will be certain to update this review after some quality time with this mug. It has... grown precious to me.UPDATE (1 Year Later)We have spent so long in the law school, yes, Precious... It tooks our hairs, it tooks our sleep. It isn't fair, is it Precious? So long since we have seen the Yellow Face. We don't needs it, Precious, we have each other. We takes what's given to us. Precious is strong. We have washed the Precious in the dishwashing machineses again and again and Precious is still Precious. Precious doesn't leak or burn or choke us. Studentses want my precious. Wicked, tricksy, fat studentses! They sneak and steal. They try to takes it for themselves. We hates them! We curses them! We bite their fingerses off! But Precious will never leave me, oh no, Precious. Now we can hold the Precious forever. We learned to type notes with our toeses.