It seems to be a very high-quality construction, in the first uses it is perfectly waterproof and does not leak, it maintains the correct temperature for a long time. With a capacity of 600ml, you can fit everything in it.
The only "drawback": the transparent lid does not screw on but fits with a rubber flange on top of the cup, I have some reservations about how long it will remain waterproof, that's why 4 stars instead of 5.