Naturally shaped, soft, silicone nipples - ideal for breastfed babies to eliminate nipple confusionnDual anti-colic vents prevent unwanted air intake and reduce colicnComotomoTM replacement Nipples grow with your babynSafe in microwave, boiling water, dishwashers and sterilizersnMade of 100 percent safe hygienic siliconenKeep using your Natural-Feel Baby Bottles™ as baby grows! These extra silicone nipples are available in a range of styles and stages to keep up with maturing babies. Pack of 2. Comotomo™ Natural-Feel bottles sold separately. Slow Flow features one hole (for newborns-3 mos.), Medium Flow features two holes (for 3 mos.-6 mos.), Fast Flow features 3 holes (for 6 mos. and up), and Variable Flow features a Y cut (for 6 mos. and up) Ideal for breastfed babies who take an occasional bottle or for transitioning nursing babies to bottles Unlike plastic, silicone is a natural material that has no open pores to harbor bacteria. Scratch resistant, hypoallergenic and BPA-free. Top-rack dishwasher and microwave safe. May be boiled.