If you are doing a single-sided pump, does it matter which pump you use?

No, it does not matter which pump you use. Each side of the Wearable Breast Pump is designed to work on either breast, even if the app tracks the device as “L” or “R.” The app’s labelling is for tracking purposes only and does not affect pump performance. However, using the correct Breast Cushion Insert size is important for optimal comfort and effective milk expression.