We were very happy with our Dr. Brown's bottles. But we switched to Born Free after learning about the bisphenol-A scare. We used the BF bottles for 2 months with no problem but now the silicone vent is broken. The middle tip of the vent (the part that points downward) somehow has a slit in it. This makes the nipple collapse and frustrates the baby. So far, I cannot find replacement vents. We'll likely return to the Dr. Brown's bottles. These were too expensive to break after only 2 months. I would not recommend these until the replacement parts become available.