I was told by everyone that these bottles were the best! I don't know why the people who recommended them never had a problem with the leaking but I sure did! The worst was rushing to feed the baby because he's screaming and then having to remove the bottle from his mouth to fix the leaking cap/nipple.I wish the people at Avent would read these reviews. Maybe the bottles I bought were part of the "defective lot" but I spent so much money on 10 bottles and I threw out the pkg. so I just keep using them - making sure the bottle doesn't leak BEFORE starting a feeding is a MUST now. Maybe I will try the playtex bottles when the time comes to advance in nipple flow before I spend the money on 10 #3 Avent nipples.