The Playtex Nurser Drop-ins Nurser Bottle Liners in 4 oz capacity are pre- sterilized disposable individual bottle liners for Playtex nursery bottles. These fit the vented angled Playtex bottles,liners that minimize air and gas issues. The Drop-Ins model from Playtex offers a convenient and hygienic solution for feeding your baby with its disposable liners that make cleaning up easier. Perfect for on-the-go use, too!