Not quite as leak-proof ...

My son has two of these cups since he was 12 years and copes well with it. Drinking works great, the assembly is somewhat complicated, but after a few times has mans out then. Super is that there are straws for exchange, because after a while they are shabby.

Unfortunately, the cup is not really leakproof. As long as he is transported in an upright, there is no problem, and the child may not be covered themselves while drinking (or keep diagonally), but tilts the cup around and is (for example, a long time in the case) already occurs a lot of water, also if it is assembled correctly.

At first I thought that would be the cup and have therefore bought a second, but it always seems to be so. We use the cup still daily and are satisfied on the whole.