Playtex Baby Drop-Ins Liners are a convenient and hygienic solution for bottle feeding babies. This product includes 2 packs of 150 liners each, for a total of 300 liners, and 4 oz nurser bottles. The liners collapse as the baby feeds, reducing the amount of air the baby ingests and helping to prevent colic. The liners are pre-sterilized and disposable, making them easy to use and clean up.