A very important thing that Medela offers is that you can find a wide range
of breast shield sizes, so you'll find one that suits you.
If the breast shield on the pump is uncomfortable, you may need a different size — Medela has
several breast shield sizes larger and one smaller than the one that comes with the pump.
Using breast shields that fit well, they should be comfortable, not compress the breasts or damage the nipples; a range
of breast shield sizes are available if the tunnel is too tight
If you feel discomfort while pumping or still feel full after a pumping session, it may be a sign you need to change
your breast shield size for one or both breasts.
The other thing that I thought of is
breast shield size.
So be sure to monitor how your nipples feel and how much milk you are pumping as changes could indicate that you need to make
a breast shield size adjustment.
To help you obtain maximum comfort and pumping efficiency, Medela offers five
breast shield sizes.
Medela PersonalFit ™ Connectors allow you to personalize
your breast shield size for pumping efficiency.