I do love these storage pots. I have a Tommee Tippee breast pump and one of these came with it. I like that they are made so that they will slot inside the bottle you attach to the pump. I don't use the pump anymore because I bought a Medela one but these are still great because they stack in the fridge saving space, keeping your milk sterile, they also have a ml mark on the side and are just the right size for me to store the milk caught by my breast shells.
BUT when I ordered these pots (and I don't know if this is a general problem or specific to the ones I got) I found that the lids are awkward. I have had to number each pot and corresponding lid because only one will go each pot and you have to find the right one otherwise they don't shut.