Medium flow nipple with 6 nipple holes provide a natural and comfortable feed, just like momu0026#39;s breast. Nipple also comes in 2 other flow rates, 3 holes for slow flow and 9 holes for fast flow. Nipple can only be used with NUK Simply Natural bottles.nSuper soft silicone nipple is the same shape as momu0026#39;s nursing nipple for a familiar fit. Flexible nipple moves with baby for a continuous latchnAdvanced 1-piece Anti-Colic Air system helps reduce colic, gas and spit upnRecommended by 90% of Moms - based on a July 2015 home use test. Momu0026#39;s agree that they provided their babies with natural, close-to-mom comfort.nOdor u0026amp; stain resistant crystal clear Tritan bottle is BPA FreenIntroducing NUK Simply Natural bottles are simply the best way to combine breast and bottle, because they're designed to be closest to mom's breast. Unlike most, the nipple has multiple holes, because mom's breast does too. Medium flow nipple comes with 6 nipple holes made of super soft silicone and provides a natural u0026 comfortable flow for your baby. The comfortably familiar nipple feels, works and moves just like mom's for a comfortable latch. Advanced Anti-Colic Air System makes feeding time more comfortable for everyone. So now, baby has a close-to-mom feel never before found from a bottle. Make the transition between breast and bottle as natural as ever. So that no matter how feedings happen, you can always share that special connection with baby. NUK Simply Natural bottles are BPA Free and easy to use, clean, and assemble and are dishwasher safe. When feeding your baby, the vent should be under baby's nose with nipple holes on top.