I bought and compared three tumblers and am posting this review on each of them. This is long, but the bottom line is, I think, that the cups all perform about the same.There are dozens of brands/styles of “double wall vacuum insulated” cups and tumblers available with very little about their listings and reviews to distinguish one from another. I spent a couple of weeks with most of my spare time devoted to reading these specs and many of the reviews. My goal was to find a brand and style that I could order several of, preferably each in a different color, to have as the main daily use cups in my home. I wanted one big enough that I don’t have to refill my cup before being satisfied but I also wanted something that would fit on the smaller shelves in my dish cabinets. And I wanted something that could be run through the dishwasher on a semi-regular basis. Once I got looking at the specs I decided that the 20 ounce tumblers were the best size for fitting in the cabinets and would allow me to pour in a 16 ounce drink and still have room for a lid or some ice, though I didn’t rule out something a little smaller. A mock-up of a 22 ounce tumbler left me feeling it was taller than I wanted on my desk and also that it was skinny enough that I worried about its stability, that it would be too easy to knock over. The desire to be able to put it in the dishwasher led me to focus on ones that used powder coating for the color, as vinyl wraps seem to not do well in that harsh environment. And a travel lid would be nice but not necessary, so a tie-breaker but not a criterion.The price range for tumblers that matched my requirements ranged from about ten bucks each to as much as thirty-five. Even ignoring anything that ran more than twenty dollars, there were still too many to choose from. I looked for brands that also had a smaller tumbler, no more than 12 ounces, that would complement the larger cups while being good for spirits or wine. And I concentrated on brands that had at least 8 different colors. Then I narrowed the selection by rejecting tumblers that obnoxiously put a brand name or logo on the side.I decided to get one tumbler in each of three slightly different styles for subjective comparison and some shoot-out tests. The 20 ounce tumblers come in three main styles. The first are straight sided, slanted to a top larger than the base. The second are what I call contoured - where the top is larger than the base but the side has a curve - which I think is prettier. And the third has a rounded base - almost like the bottom of a sphere - many of which are described as a stemless wine glass.I purchased two different contoured tumblers, each 20 ounce, and one 16 ounce tumbler with the rounded base. I went with one from Meway, which has a relatively gentle contour, one from Tahoe Trails, with a more swooping contour, and for the 16 ouncer, one from Clear Water Home Goods. I ordered all three in purple so I could see how close the colors matched. For the record, the Meway was a solid purple but looks a little washed out next to the Tahoe Trails, and the Clear Water looks more dark blue unless you see it in a strong light.They all came boxed, each included a lid (though only the Tahoe Trails lid could be closed, the others have a permanently open sipping slot), and the Meway also threw in steel straws with a cleaning brush. To my not very practiced eyes, the inside dimensions and shape of the two 20 ounce cups look the same, so I measured the actual capacities. Both of the 20 ounce cups will hold 20 ounces if you fill all the way to the brim, but they will only hold 16 ounces if you fill to just below the space needed for the lid. The 16 ounce tumbler, on the other hand, will hold 16 ounces with the lid in place and 18 without. This makes the 16 ouncer much closer to the 20s and rather more desirable for its shorter height, though it is also a consideration that it doesn’t fit in my car’s cupholder while the other two easily do. The Tahoe Trails is 7 inches tall, the Meway is 6-3/4 inches tall and the Clear Water is 5-3/4 inches tall (but wider than the others at the base).There are no markings on either the Meway or the Tahoe Trails, but the bottom of the Clear Water has indented text that identifies the manufacturer as Polar Camel. If you search on “Polar Camel” you will find literally thousands of tumblers with engraved text or graphics. I paged through all those listings and the Clear Waters were the only ones I found that were not engraved. Polar Camel says (on the bottom of the cup) “hand wash only” but as it’s powder coated I chose to ignore that.Functionally they’re pretty much identical. The outside of the Tahoe Trails is noticeably (though not significantly) larger. I think that might mean the vacuum space is larger on the Tahoe Trails, but it didn’t seem to make a difference in performance. I filled them with crushed ice, put the lids on, and left them undisturbed on the dining room table for 24 hours, when the average temperature in the room was about 76F. For a control I used a 20 ounce glass mug. The ice in the glass mug was reduced to a few floating slivers after about 5 hours, the vacuum tumblers all had about a third of their ice after 24 hours. I then repeated the test (minus the control) with the lids off. Unfortunately the weather didn’t cooperate so the temperature in the room was about four degrees hotter. Not enough to invalidate the results but enough to skew them a bit. With the lids off, the ice in the 16 ounce cup was reduced to a few slivers in 21 hours and in the twenty ouncers there was only a tiny bit left at 24 hours. In general the ice seemed to be melting about twice as fast with the lids off.Having determined their functional parameters, the next thing to do was to get some data on their durability. To test this I used my dishwasher. There are two dangers in not hand washing these cups. The first is that the colored coating may become damaged, either cosmetically or physically. The second is that the temperature changes can cause the seal to lose integrity. If that happens you get reduced to the tumbler no longer keeping things cold or hot for significantly longer than a regular cup. Both of these reasons are why most manufacturers recommend hand washing only.Over the course of a a week or two I ran all three through the dishwasher whenever I had a load ready to go, so about five or six times. To better protect them I always put them on the top rack. The cups have all remained fully functional, continuing to keep things cold for as long as I needed, but I didn’t do any torture tests or any additional timed shoot-outs. The Tahoe Trails cup did develop some spotted discoloration but I can’t say if that was just an unlucky cup or if they might use a different composition of coating than the others. The reviews for these tumblers are filled with people that either machine wash them with no problem, or who have done so and had their cup ruined. My belief is that this is a potential problem but relatively rare; if it happens to me I’ll buy a replacement and not rail against the manufacturer. I’d rather take a small chance than have to treat my cups as sacred objects.Let’s also take a moment to talk about the most repeated complaint about the Tahoe Trails tumbler. The lid. The lid has a pivoting piece of plastic that locks into a down position to seal the cup completely against leaking (I didn’t test this). The complaint is that in its open position this bit of plastic sticks up, higher than the lip of the cup, making it push against your nose if you try to drink by tilting the tumbler instead of your head. This complaint is completely valid, but is also about the same as drinking directly from a soda can whose pull-tab is in place. You can decide if having to tilt your head back when you drink is a deal killer or not, but this could definitely be a problem if you plan to drink while driving. You can also consider buying a third party lid if you really like the look of the Tahoe Trails tumblers.So, as I said at the start, they all function about the same, have slightly differing aesthetics, and slightly different usability profiles. The technology seems to be mature, so it doesn’t much matter which brand you buy. Pay attention to the form factor if you intend to put it in a car’s cup holder. Get the stemless design if you don’t want to take it in the car and want it to not look huge. Get any color or design if you intend to hand wash only but probably stick to ones that are powder coated if you want to run them through your dishwasher.If you have any questions that I didn’t cover, comment on this review and I’ll try and check in to answer them.I wish they made it with a handle. And make a pitcherFantastic product. Use it for work to transport my iced coffee and tea from home to work. Drinks stay cold forever. Didn't believe drinks stay hot or cold for hours as advertised- but I do now. Like from 8:30am till 4pm its still cold! refreshing cold. Not just cool or lukewarm. I was/am amazed. And they look good too, feels like quality. I love them.Love themGoodDid not like getting the cracked lid. I do not want to go through the hassle of returning the order.Bought for road trip.. could hold ice longer but nice tumblerUse mine all day everyday . Love it.One was scratched up, but I only needed 6 so, it’s fine. I’m not sure how it was damaged, the box came as a case, like they were packaged that way. I ended up covering the worst of the damage with a decal, and it’s just an extra so I’m not super worried about it.But just be aware that sometimes one might come damaged.I only received 4 cleaning kits as well. Which is fine, I can just use a sponge, or something but. Would have been nice to have 6 so the wedding party all has their own full set up, straw, cleaning kit etc.They’re very pretty. Vinyl sticks to them.Only downside is that it weirdly comes with only half of straw cleaner and half of something that I’m still not sure what it is. All the ladies loved it!They turned out better then I thought they would. They keep beverages cold for long periods and hot for long periods.La verdad fue un regalo y me comentaron que ha sido muy útil y que está muy bonito. Lo usan para el café y me dijeron que no se ha derramado mientras la persona va en el carro.Encargué el color rosa y está hermoso, de muy buena calidad, viene con su popote de metal y cepillo para lavar el popote. Las bebidas duran bastante tiempo calientes, muy práctico para invierno. Lo recomiendo.