Tommee Tippee Advanced Anti-Colic Bottle Set

I had high hopes for these bottles, but poor quality control is quite problematic. These bottles are advertised as anti-colic. This is accomplished by providing a vent which allows air into the bottom of the bottle, eliminating the suction drawing air back through the nipple and introducing air into the milk or formula. There is a vent at the bottom of the tube, which is vented through a hole underneath the outer rim of the lid/nipple. This kit comes with six bottles. Of the six bottles, four had major issues. The nipples would completely collapse under the vacuum created from feeding, and would then draw air back through the nipple, adding all the air these bottles are designed to eliminate. This shouldn't happen on an anti-colic bottle that vents to outside air. Upon inspection, I found all four bottles that were malfunctioning lacked the slit in the silicone one way valve. It was never able to vent because there was no passageway cut in it. Frustrated, I used a new sharp razor blade and cut the slits myself. This took care of most of the problem. Unfortunately, only having one hole under the cap, it can still be temperamental. Making sure the vent hole is on the top helps, but you then have to remember where it is positioned since you can't see the hole with the lid on. That's easier said than done on a round bottle. And still, sometimes it acts up for no apparent reason. Taking it apart and reassembling it mid-feeding usually corrects it, but babies aren't usually patient and understanding when it comes to stopping their feeding time. I think the design is good. I think the quality is poor. I also think there needs to be a slightly slower flow rate than the rate the number 1 nipples flow. I feel my two stars are generous, especially considering 2/5 equates to a 40% when only 33% of my bottles came without manufacturing defects. And of the 33% (two good bottles), they still only work correctly about 75% of the time. Bottom line, I don't recommend these bottles at this time. Maybe if they step up their quality control it could be a good bottle. But I have lost faith in the product and will be trying something different. There are cheaper, especially if you get the standard bottles and forgo the anti-colic, which these bottles don't really have anyway.