Continue that special breastfeeding bond, even when you cant breastfeed. Introducing NUK Simply Natural bottles are simply the best way to combine breast and bottle, because theyre designed to be closest to moms breast. So now, baby has a close-to-mom feel never before found from a bottle. Unlike most bottles, they have multiple nipple holes (up to 9) because moms breast does too. The comfortably familiar nipple feels, works and moves just like moms for a comfortable latch. And the Advanced Anti-Colic Air System makes feeding time more comfortable for everyone. 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 9 oz bottles are BPA Free and come with a medium flow nipple with 6 nipple holes. The Tritan bottles are odor & stain resistant and are easy to use, clean, and assemble and are dishwasher safe. When feeding your baby, the vent should be under babys nose with nipple holes on top. -Multiple nipple holes provide a natural feed, just like moms breast. Nipple comes with 3 to 9 holes, depending on flow rate. 9 oz bottle comes with medium flow nipple that has 6 holes. -Advanced 1-piece Anti-Colic Air system helps reduce colic, gas and spit up -Recommended by 90% of Moms based on a July 2015 home use test. Mom's agree that they provided their babies with natural, close-to-mom comfort. -Odor & stain resistant crystal clear Tritan bottle is BPA Free & assembled in the USA.