Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Do their job, but a pain to clean

Our baby was very gassy/spitty, so we decided to give these bottles a try. They do definitely help, but they are also a huge pain to clean, requiring a special tiny brush (included) to get all the nooks and crannies of the little parts. We also tried the bottles with the disposible plastic liners, and those work to keep air out too with less muss and fuss, but now that he's trying to hold the bottle himself they are less practical and so at 10 months we still use these bottles (and wash them, and wash them) every day.