I used the Aventi or something like that (the ones that make the fancy bottles) they were great, had to use them until DS was 9mth old and then weaned him off. We went on to BF until he was 2yrs old. I had lots of people tell me not to use them and to get rid of them as soon as possible but the best advice was from the ABA - just do what you have to do to BF. Another good tip was to let bub have a go at BF without the shield at the end of the feed as it helps to encourage your immunity that you then pass on to bub