We transitioned my son to these bottles at 7 months. He had been getting one traditional bottle a day up to that point to supplement breastfeeding, but I never ended up producing enough so that number continually increased until I almost had to wean. I desperately wanted to continue breastfeeding though, and I found these bottles. They may have saved my breastfeeding journey, as we are still going strong. They certainly saved me some pain! He stopped biting me when we switched to babaloo because traditional bottles flow faster when the nipple is bit, these do not. He also can eat even quicker with these if he wants to because the speed is really controlled by him. The slow flow nipples have always been plenty, he is 11 months now and he finishes a 5 oz bottle in about 90 seconds. We are just having to buy replacement parts now after 4 months of using each bottle once a day, we run them in the dishwasher at night. These have been a blessing and I recommend this company to all my mom friends.