***Perfect for Preemies and Beyond***My Twins were born at 34wks and struggled with the Avent Bottles the Hospital recommended. I bought these bottles after reading the reviews, hopeful it would reduce the severe colic and gas they were having. I noticed a difference after the first two feeds, my Babies were less fussy and did not need to be burped as much before falling asleep. After a full 12hrs it was like a miracle! My precious Babies were able to take a feed, be burped, go to sleep and stay asleep with no gas or fussiness! I couldn't believe the difference! They are now 7mo's old and I still use Dr. Browns. I transitioned them from a Preemie flow to a (now) '2' and they've done great with each phase. Even the extremely painful re-flux my second Twin had has dramatically reduced and he sleeps just fine. I've included a helpful list for use below and highly recommend these bottles to anyone needing a solution to help those tiny little tummies adjust.*Dr. Brown's Bottles come with several pieces and it is important to individually wash each one to avoid build-up and/or residue.Allow each piece to dry fully before use as bottle lids will not seal when wet and leaking can occur. I recommend a drying rack and purchasing more than two bottles for convenience/time-saving.**Make sure to use the small brush for the crevices of the flow-device. Build-up and residue can occur, even with frequent washing/boiling. So avoid this by brushing and airing at least every other day. Keep nipples clean by soaking in very hot, soapy water. But do not boil them everyday as this breaks down the firmness Babies need for proper sucking. I recommend a Preemie-Flow for Infants-2mo as severe colic can make it hard for Babies to take a faster flow. Then ease into a '1' by switching out the nipple for 1-2 feeds a day. By the time Baby is 4-6mo, a '2' can be used and should cause no issues.**Lastly, do not prepare Formula/Breastmilk and heat in bottle. Prepare and heat Baby's milk in a separate container. This will avoid leaks and ensure a good seal when milk is poured into bottle. This also prevents hot-spots and ensures an even temperature for Baby. The Dr. Browns Bottle warmer is an excellent way to ensure that the milk is properly heated and I highly recommend it also.*I hope this review is helpful as I know firsthand how overwhelming it can be to find just the right bottle for your little one. I wish I'd known how wonderful these Bottles were with my first Baby. It would've made life so much easier! Thankfully I discovered them with my Twins and sleepless nights have become fewer and fewer. Dr. Browns Bottles are simply the best!Signed,A Very Happy Mommy!