It is robust. The "metal spiral spring-ball" makes the whole thing to a simple and once bolted, the thing remains completely sealed. The flap, which closes the drinking opening, also is tight and will not open on its own.
In the event that he or leaking should be sharp at the drinking hole, you have to Shaker simply swap. There was a few times reported it and I can only say that it is completely processed top with me.
Another goodie you can still tuck powder or other dietary supplements in the shaker. It is stored in a double-chamber socket that can be screwed further down.
In sum, a well-designed and also well-implemented product that deserves 5 stars.
