We recently bought three of these bottles. We still use them when the others are dirty, however, THESE BOTTLES ARE HORRIBLE!!!! They leak at random. The worst part is that it doesn't happen all the time, so you never know when you are going to end up with a pool of milk at the bottom of your diaper bag, or will it wait to leak all over your baby. We've found that no matter when it happens it's a pain to have to clean up after a leaky bottle.While there are more little parts to wash, the Playtex VentAire NEVER leaks and seems to do a better job of keeping the air out anyway.WARNING: The Avent bottles are the worst for leaking. Do not invest in these. This was our biggest baby item purchase mistake.