We went through probably clost to 10 different brands of bottles with my bottle refuser before she finally accepted these ones. We’re now going on 2 months strong of using these every day at daycare. She is breastfed and has no problems switching back and forth. We even went on vacation and she didn’t get a bottle for a week and went right back to drinking from a bottle at daycare. The flow levels on these aren’t the same as other brands so there’s no need to stay on a lower flow for breastfed babies. I think we started with level 2 but it was taking her forever to finish a bottle so we tried out level three and it has been great. She doesn’t seem to have any bottle preference