When you fill them with warm milk and close them up then either (1) remove the cover or (2) turn the bottle upright, there is significant leakage! In case #1, out the teat. In case #2, through the valve in the base. Not good.
I have, however, figured out how to avoid all leakage! Yay!
What nothing I have seen tells you, including Adiri's web site/FAQ, is that you can avoid leakage if you add a couple of simple steps to the regular filling instructions.
- Push body of bottle firmly into cover and set on counter upside-down.
- Pour in warm milk.
- Attach base and firmly tighten.
- Wait a minute or two.
- Push down on the valve through one of the flower-pattern holes in the base to relieve pressure.
- Turn over the bottle and from now on stand it upright.
For #5, I use the tine of a fork unless it's been a long time since I cut my nails and my little fingernail is long enough.
With this simple discovery, I went from being frustrated greatly by the Adiri bottles to finding them very good indeed. The only other issue is that without purchasing additional components you cannot actually warm milk in them but I warm the milk prior to pouring it in and our baby seems to be ok with drinking the milk without re-warming for quite a few hours thereafter. If you need to, you could always pour the milk back into the bottle you originally warmed it in for re-warming, though I have not resorted to that as yet.