Curious, not many people have reviewed this specific item, nor have I met any who own one.

There is an interesting story to this. I have been into vacuum flasks a long time (11 years). I am hiking Pikes Peak and other Colorado mountains, and wanted better retention of temperature while also being pressure proof to changes in elevation-a problem that causes some bottled water to explode or leak. I needed the best out there.

Many companies-and I mean many, perhaps over 50 created new vacuum flasks over the last few years. I have used Stanley, Thermos tm., Fifty fifty, Yeti (had to return the Yeti immediately due to dent caused by seller) and more, Contigo, house brands, Etc.
All of these seemed to be focused on ease of use, drink ability, cleaning, what-so-not, everything other than temperature retention performance since they are being used at home and not for serious applications like hiking or work that is far from cooking and in a cold environment or very hot environment.

This piece from Stanley is intriguing as it is focused on truly good scientific temperature retention. It can outlast the heat of most coffee brewing dispensers, which is a very high standard. The 47 hours hot is a real peach. The performance is indeed quite great. I have tested this against my 5050 growler 2 quart and my 2 liter Thermos (tm) and it absolutely does better with a hot liquid. And cold is also better slightly.

For a serious actual trips onto mountains this is the most useful flask I've ever come across. a 20 hour hike of which requires me to use hot water for meals and tea making without the time consumption of setting up a stove and the weight of fuel, this makes my hike much faster while still having a hot meal.

Recommending this can not come soon enough, but I have taken a couple weeks to test it out and held in my excitement to find any possible negatives. Objective negatives, things I think Stanley could do better, there is only 1. I'd like to see them use the same rubber bottom Vacuum insulated cap cup they use on their master series 1.5 quart (a close contender to this but is too small in capacity for my uses, I actually use 2 of these 2 quart bottles on some trips) for better heat retention when pored into the cup, as well as just slightly better retention with the main flask. And this cup is only metal, without the rubber bottom it slides around on rocks and slanted surfaces.

However, I may let you know if you use the cap cup with hot liquids, it is actually a convenience that the temperature cools quickly since it may be literaly too hot to drink from when used as a hot beverage. An insulated cup may require you to sip more carefully as it could be literaly too hot.

There is a subjective negative as well. To have such great performance, the cup must have some more weight to it. Stanley can not do better here, it is a scientific trade off for the required amount of material for reflecting heat and two extra walls for a better vacuum system.
I'm not sure if quadvac uses two different vacuum walls, like wall 1, vacuum, wall 2, then reflection then wall 3 then vacuum again then wall 4, as that's how I imagine I'd do it, but however the system it requires extra weight even for the size of container.

If we want to split hairs with subjectivity another color option would be nice too but I love this nice green, much more than some of the other green Stanley has produced.

Anyone who is serious about through hikes and outdoor sports, or who may be busy as a police officer and what-so-not and need long term thermal retention this is for you.

And I have tried, nothing else even comes close, and I mean it. If it does let me know and show me the proof. Hands down this is the best serious high performing vacuum flask that you can find in stores or on the internet for civilian use.

Although I have only used this particular thermos for a little over a week and get me to the claims that Stanley has poured as far as keeping things either very hot or very cold. I had not followed Stanley’s recommendations on the size of thermos to get for the 10 quart lunchbox. And decided that the dimensions of this thermos should work extremely well with the lunchbox however, it is just slightly too big even with the cap off disappointing it’s an excellent thermos and holds quite a bit of coffee. I opted for the thermostat fit in the lunchbox for convenience, so I did not have to keep track of two different items. I will find a use for this thermos as it works very well.

This is a perfect thermos. I got the 1.5 qt size which is plenty for my coffee. It keeps it too hot to drink all day, even when my power went out and the house dropped to the mid 50s. The outside is cold so there is no noticeable heat loss. The lid works well with about 3-4 turns to open it enough to pour coffee out, then screw back down. There are a couple of channels that allow it to work as a pouring carafe and little arrows to identify where to pour. That design is good as it keeps the lid on to pour for less heat loss. The handle is good and it is attractive. But best of all is it keeps my coffee hot all day.

This is awesome. Very happy with my purchase. Packing and postage are up to your usual excellent standard I will be keeping an eye on your eBay store for sure