Willow Sizing Insert Set (2-pack)
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Find your flange fit. Pump with confidence.
When it comes to wearables, sizing is different — you'll need a fit that's more snug. Most moms find that adding 1-3mm to their nipple size (or 0-2mm if you're pumping with Willow 360) results in optimal output and comfort.
Still need your nipple measurements? Try our sizing guide
Measured Nipple Size |
Willow Recommended Size Flange / Insert |
9-11mm | 13mm insert in 24mm flange |
12-13mm | 15mm insert in 24mm flange |
14-15mm | 17mm insert in 24mm flange |
16-17mm | 19mm insert in 24mm flange |
18-20mm | 21mm flange |
21-23mm | 24mm flange |
24-26mm | 27mm flange |
Sizing inserts can only be used with a 24mm flange or 24mm container insert.
Questions? Our experts can help.
1-888-WILLOW-3
How To Find Your Nipple Size
Step 1: Get a measuring tape
Measure the diameter of your nipple at its base while erect to determine its size accurately.
Step 2: consider sizing up
Most moms find that adding 1-3mm to their nipple size results in optimal output and comfort.
Step 3: take a look at our chart
Match your measurements to our sizing chart to find your recommended size flange / insert.
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- Fit into our 24 mm flanges to improve comfort and output for moms who measure smaller than 21 mm
- Flexible silicone material provides a snug, secure fit
- Compatible with Willow 360, Willow 3.0, and Willow Go flanges
- Dishwasher safe for easy clean-up
- Made without BPA for a safer pumping experience
Use the Willow Size Guide to measure nipples and find the insert size that's right for you.
*Please note sizing inserts can fit into 24mm flanges or containers only.
2 Sizing Inserts
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Replacing Your Parts
For optimal output, replace every 90 days (or when you notice discomfort or signs of wear).
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View all- Brinne L.Verified BuyerI recommend this productRated 5 out of 5 stars43 minutes agoGreat addition
I was really happy to see they are offering sizing inserts now. Even if you don’t need to size down the flange, I feel these offer more comfort during pumping, especially for anybody with elastic tissue.
Was this helpful? - Cambry B.Verified BuyerI recommend this productRated 5 out of 5 stars19 hours agoLove
I love that these have the size included on them as I fluctuate and am constantly rotating my inserts. I had to write the sizes with sharpie on my other pump inserts and have to always redo it because the sharpie washes off after a few washes.
Was this helpful? - Taylor C.Verified BuyerI recommend this productRated 5 out of 5 stars23 hours agoGreat customer service!
I was having issues with leaking and thought maybe the flange was too big. Customer service was excellent and followed up multiple times to fix the issue. The flange inserts were exactly what I needed and have been great.
Was this helpful? - Sharon M.Verified BuyerI recommend this productRated 5 out of 5 starsYesterdayIt works well
I had to go up a size and I’m glad I did. The inserts are great to create a better seal and feel more comfortable, get better output, and keep the pumps stable. Measurement is important, don’t skip it!! After measuring, make sure you check the corresponding flange size. I recommend measuring at the end of the second trimester or third trimester.
Was this helpful? - Autumn C.Verified BuyerI recommend this productRated 5 out of 5 stars2 days agoFit perfectly
Perfect fit. I used the sizing guide included with the pump and the inserts I ordered fit perfect.
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