It never leaks, it's effortless to use one-handed, it keeps drinks HOT! A perfect mug!
I will confess first, before I begin, that I have a pretty strong bias toward Japanese products. This is going back to the days when Sony had no equal in electronics, and when Toyota/Honda were leading the small car revolution. With that said, please forgive me if I sound too impressed with this home run of a mug purchase.I had heard that zojirushi made good products, but I've had some bad travel mugs and figured it could have been just another cash-in on brand power. I ordered the stainless steel 12oz because I needed a small one for easy travel (most of my travel is on foot or on bike, living in a big city and all), and when it came, I did thorough investigation of its capabilities.Immediately, I went to the kitchen sink. I filled the mug with water, sealed on the cap, locked the lid, and proceeded to turn it sideways, hold it upside-down, swing it around, shake it vigorously (while still upside-down too!), I pretty much did everything I could, short of anything that might damage the mug. Not a single drop came close to wetting my hand or anywhere else. I even wiped the counter with a rag afterward, just to see if I missed something. It was bone-dry.Next came Coffee. I love coffee, drinking several cups a day and switching to decaf so I can drink more in the afternoon and after dinner. I filled this mug up with fresh coffee, and even half an hour later I almost had to nurse drinking it to avoid burning myself; The coffee was practically just as hot as when I had poured it. I proceeded to comfortably drink hot coffee for several hours without any need to reheat or refill my mug (except of course, for more coffee). Amusingly, it even kept coffee hot longer than the insulated coffee pot did! (funny that one, maybe I should get a zojirushi coffee maker too)Lastly, the ease of operations challenge. They claim that it's easy to open this mug, drink, and then close it, all with one hand. I will admit, at first it took me a little bit of getting used to the operation, but within a few days at most I was using it fluidly with one hand, which was perfect for my commute, or when shopping at busy downtown markets. I could walk through thick crowds (this is pre-covid of course) and not have any problems with opening it, drinking more coffee, and closing it. Of course, it was still hot even when walking in the nippy winter air.This really is my idea of a perfect travel mug. You can't make it leak (even when you throw it sideways into a purse for a few hours), you really can use it one-handed, and it really does keep the drinks hot. I've done tea in this as well and it was just as good an experience; Never tried hot cocoa as zojirushi advises against milk products being used (If I recall correctly, it was something to do with the pressurized, sealed containers being able to build pressure due to milk doing what milk does). Regardless, what I've asked of it, the mug has proceeded to do with flying colors. I cannot recommend this mug strongly enough. If you ever find yourself wanting to have a small, reliable, and easy-to-use travel mug, then you cannot go wrong with zojirushi.