The build quality is great (pleasantly heavy and high quality) and the cup is 100% leak-proof! He should be rinsed after use always with hot water - also in the field of poetry - so he will remain tight. The shutter is very easy to use (just press it = ON ... press again = TO SEALING & ...) and can be quickly and easily disassembled into 2 parts, making it very easy to clean. Through the sleeve (there are the same cup without collar), he is very comfortable to hold - even in cold weather outdoors without gloves.
Before buying I was initially a little unsure myself, as I have read in one or the other review that the cup after use difficult to open and is leaking after a while. The is but not so or the reasons that my opinion on an incorrect handling (eg seal not clean / vacuum in tight cup before opening / ...) are based.
Therefore, my conclusion is: Anyone who observes the instructions in the manual, will have long joy with this Termobecher!