Enfamil Standard Flow Soft Nipples are ready-to-use, come individually wrapped, and vented to allow air flow while the baby is sucking. They will fit most bottles with standard or classic size bottle openings, including our Nursette bottles, Enfamil plastic bottles, Enfamil Grad-U-Feed nursers, Mead Johnson Cleft lip/Palate Nursers, and Snappies.