Since the birth of my daughter we had bought on the advice of mam bottles supposedly anti colic however after some time my daughter was screaming for the bottle nipple became blocked when milk was not thick, we made several test and we find the solution to all our problems with these bottles certainly the flow is a bit fast but it the ideal anti colic system works great swallows more or almost more air no longer weeps during suckled except when was thickened milk for rgo sometimes you have to go to the nipple L but it is a glutton and gets upset when things are not going fast enough. I highly recommend this product for me is appreciated and solved many things for my daughter 3 months.