I now have been using these bottles for several months. I very much disliked them in the beginning since my husband hid the vents so they leaked. Luckily I did not throw the bottles out... since I found the vents which stopped the leaking completely. I am not happy with all of the parts to the bottle- it makes for difficult cleaning & sanitizing. I do love that they are BPA free. My son loves his "baby bottle". Great quality, but very expensive.