These are just about the most basic storage containers you can buy. I got them for the value, most storage containers have to be purchased online for me since the stores where I am don't carry many choices. These seemed great for transporting milk from point A to point B. The issue I have with them is the quality. Our baby is breastfed and we work so there is A LOT of sterilizing going on. When you put these in the sterilizer, following the basic instructions of the machine you have, the bottles bubble at the bottom, making them unable to stand upright. This was an issue! We tried to manually push the bottom bubble back in to force a flat bottom which kinda worked but not really. Not worth the time - annoying. So we wrote to Medela and they were nice enough to replace them - but from now on no sterilizing! The bag for sterilizing from Medela is fine but it only works 10-12 times and you have to get a new bag - no thanks! I already have a sterilizer! I'd rather use that....but I can't. So we have to use our sterilizer with very little water - aka, we have to sterilize these bottle on their own with no other item combined. This works. Just annoying.

The tops are definitely different than pictured on the box, and I don't think they seal as tightly as the other tops, but they still work. Others said the bottles themselves seemed to be thinner than other Medela bottles, but it's not too big of a difference.

UPDATE: I haven't been using these for very long, but there is most certainly a difference!!! I'm leaving my original review (what is typed above), but removing my original 4 star rating. Why? Because almost all of these bottles have warped in my dishwasher. I wash them just like all my other Medela bottles that I got with my pumps and from the hospital, but these are the only ones that have warped. The bottoms have expanded so they don't even stand up correctly, they just wobble (and obviously now the measurements are off). A serious waste of money.

The only reason I chose these storage bottles is because I've also got a Medela pump and I thought I wanna be consistent and I have this little problem of being a "perfectionist" and I thought it would be nice to see my milking station equipment and supplies to be in "uniform", and I like the color yellow. But then I realized there's nothing so special about these storage bottles and that my reason for choosing this over cheaper milk storage is so vain. But then I also realized over time as I go on with my pumping journey that these bottles are actually cute and not cheaply made. It doesn't look like and feel like a toy, compared to other ones. I'm confident that my breastmilk is safe with these . Plus, I love how readable the measurement labels are. I have about a dozen of this which I find convenient coz we have enough for a whole day even without washing.

I liked the old style of Medela collection bottles more, unfortunately (the ones that just had the clear, raised numbering). These look nice, but I feel like the old style locked in more tightly on my pump (maybe because my pump isn't the newest style?) and it was easier to tell at a glance how much was in them. With these I find myself straining my eyes to figure out if the amount in the bottle has hit between the lines for X amount or if its just under or over.

Interchangeable with the bottles I received with my pump. I ordered these as extras because I couldn't keep up with how often I was washing them since all of my breast milk is pumped. These are wonderful. They go on/off the shields easily and have very clear markings for how much is in them. I have found the measurements to be very accurate when compared to the other containers I have, including the bottles. They hand-wash very easily with a bottle brush and turned out fine when running through the dishwasher. I have not tried the microwaveable bag they come with for "sterilization."