5 Drop-Ins liners. Clinically shown: mimics breastfeeding; significantly reduces gas and colic. Bisphenol-A free. BPA free. Pre-sterilized disposable liners keep air out for more comfortable feeding. Playtex Drop-Ins disposable liners are: pre-sterilized for a clean bottle any time; 100% leak-proof guarantee; pre-formed for easy one-handed assembly and clean-up; Bisphenol-A free (BPA-free). Generations of moms have trusted the Playtex Drop-Ins System with their babies, and it continues to be the No. 1 selling bottle system (based on sales volume). It is also pediatrician recommended. Two recent clinical studies confirm that the Playtex Drop-Ins System provides significant colic reduction and mimics the natural feeding patterns of breastfeeding: Clinically Shown Reduces Gas and Colic: In a clinical study, 8 out of 10 mothers indicated that their babies showed fewer signs of gas. colic and other feeding discomforts. Clinically shown to Support Baby's Own Natural Feeding Pattern and Support Breastfeeding: Baby sucks and swallows in a coordinated rhythm that is similar to how they feed from the breast; Baby breathes more naturally; Baby can control the flow of milk, so he/she takes in just the right amount. The Playtex Drop-Ins System is designed to help baby switch between breast and bottle. Patented NaturaLatch Nipple: Clinically shown to mimic baby's latch-on like the breast; Slow-flow nipple designed to replicate the natural flow of the breast, so baby takes in the right amount. Compatible with the Playtex Nursing Necessities Breast Pumps: Just pump, store and feed using the One Step Breast Milk Storage Kit (sold separately); Easy to store and freeze directly in the liner. Latex nipple made in Mexico. Nipple ring made in China. Made in USA.