Maymom Adapter for Medela PersonalFit Flex and Sonata Breast Pump with wide mouth bottle


This bottle adapter is for Medela PersonalFit Flex Connector and Medela Sonata pump to work with wide mouth bottles from Spectra and Avent.

What we like:

  • Enables Medela Sonata and PersonalFit Flex connectors to pump milk directly into wide mouth bottle
  • Works better than Philips Avent conversion kit in terms of preventing spill with its sealing disc
Work with:
  • Bottles: Wide mouth ones from Avent, Spectra.
  • Medela breast pump: Pump in Style (PIS), Lactina, Symphony, Swing, Freestyle Flex, Sonata to work
  • Other breast pump: Evenflo Comfort Select, Ameda Purely Yours, Lansinoh Double Electric, Playtex Embrace, Dr. Brown's Natural Flow Electric/Manual
Does not work with:
  • Avent VIA storage cups
  • Spectra standard-neck bottles
  • Pigeon wide-neck bottles
  • Playtex Nursery bottle

What's included in each pack:

  • 2 x adapter with sealing ring (inside the adapter)


  • BPA free, dishwasher safe, retail pack, sealed by manufacturer.

A breast shield or flange is the funnel on a breast pump that attaches to your breast and draws the nipple out, creating suction and allowing your milk to flow out of your breasts and into the storage bottle. Some breast shields, the funnel and the bottle connector are joined seamlessly as a one-piece, known as the flange.

The size of the breast shield is express in terms of millimeters (mm). This usually refer to the measurement of the opening at end of the funnel towards the tunnel.  

Finding the Right Fit: 

In order to find your optimal breast shield size, you can measure your nipple diameter:

  1. Using a ruler or measuring tape, measure the diameter of your nipple at the base (across the middle, diameter) in millimetres (mm). Do not include your areola.
  2. Add 2 to 4 mm to your measurement when selecting your breast shield size.

If you have already started pumping, please measure after a pumping session.

You can also download this ruler, print and cut out the ruler to measure your nipple diameter.

Am I using the correct breast shield size?

If you answer yes to one or more of the following questions, you may be using the incorrect breastshield size.

- Do you feel discomfort when pumping?

- Does your nipple rub against the side of the flange?

- Do you see excess areola pulled into the flange?

- Do you see any redness of whiteness?

- Do you feel unexpressed breast milk after pumping?

A good fitting breast shield should give you a gentle, rhythmic pulling during expressing, and your breast should feel empty and soft once you’re finished. Pumping breast milk should never be a painful experience.

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