Well I discovered these bottles a few months back and spent a small fortune on them only to change to a thickened formula and dismiss them as not being able to work with all the tubes and small holes. This week I decided to try them out and I am very glad I did. This is really the most amazing product for a mamma of twins. The girls can now feed at the same time and this is the best bit- they can feed themselves and at their own pace. It only took them a few seconds to get used to the new bottles and although I still watch over it does make my life easier. I don't use them with every feed as I still like the cuddle action that goes along with normal bottle feeding. Don't be a mug like me and buy them from any baby shop in Australia, order them online from ebay- they will ship to you direct from the States and at about 50% cheaper.