Well, what does leak, it drops to just how many other bottles also. In the mouthpiece aspirated liquid remains and then passes out. My little boy (2 years) make it so, to make the half-bed wet, so when he turn sucks again and again and the liquid then (he always has at night a water bottle in bed, that's why I am so eager to run security) out shaking. The silicone part sits also right that I have checked first.
Conclusion, the bottle is not bad, just who is looking what what is really absolutely tight, which is here ill-advised. ME is NUK as better classes. Unfortunately bothers me because the large silicone insert which is as fast giddelig in the dishwasher and the Easy Learning Cup there are no longer who was really great :-(.