NUK bottle is an anti-flatulence bottle, which has an air return hole and a nipple with an air return hole. Generally, this air return hole is very slow, and the air pressure inside and outside the bottle is unbalanced, so the baby will suck milk very slowly. If you are still hungry and eat in a hurry, you are more likely to eat into the air, leading to burping, vomiting and bloating. ...
The functional anti-flatulence bottle with Bang @2 anti-flatulence valve can finish a bottle of milk at one breath. There is still a big difference between patented design and ordinary bottles!