Like every new mom, I was unsure what type of bottle to use. I bought the gift set. I used the bottles for about a month. It did help with air intake but was horrible in every other way. The seal at the bottom never sealed right. I boiled them every week like recommended. Everytime I fed my daughter, formula would leak. I started to use the normal Evenflo bottles like my mom used. They work great. My daughter is now 5 months old and has less problems with gas now then when she was younger. Due to the bottle, I don't know. But I think these bottles are a waste of money!