I know that Medela has an extra large breastshields option. That would be 30mm.There are also 24mm and 27mm options. As I understand though, the breast/cup size doesn't matter as much as the nipple size.
I agree with all the above, I currently have a Medela Symphony from the hospital, and I'm a 36DDD or something (not sure, the nursing bra I use only has S, M, L, etc), I use the medium sized flange (I think that's what it's called) but I know they had bigger ones at the hospital and at Walmart.
I am a 40G and I use a Medela Symphony. I use larger sized shields and I am still comfortable. Shields go by nipple size. I use a 30mm which is an xl. If you go on the Medela site you can get a better idea of the size you need. Size 24mm comes with all pump kits since it is the standard size.
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