These are absolute crap and if I hadn't already filled them up with breastmilk and put them in the freezer I would have sent them back. The lids don't screw on ANY of the containers correctly. There is space that I can push down on the lid and because of this when I swirl the milk after it has been refregierated with the lid on it will spill out since it is not correctly sealed.. So upsetting.
I thought maybe one or two were defective but all of them do it. I have even had other people try to screw on the lids in case I was just doing something wrong but everyone else has had the same issue.
Waste of money. Spend a little more $ and get something better quality. The cups are thin flimsy plastic too.