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Willow
Breast Pump Sizing Kit

Rated 4.9 out of 5
28 Reviewsor
$
24.99
Free shipping & returns for Babylist orders $45+
FSA & HSA Eligible

FSA & HSA Eligible

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1

Overview

Description

Find your perfect breast pump flange fit with a wide range of inserts designed for maximum pumping comfort and milk output.

The kit includes 13mm, 15mm, 17mm, 19mm, 21mm insert sets, a nipple sizing tool, pump sizing 101 guide and 1:1 virtual visit with a Willow Sizing Specialist.

Proper fit leads to comfort, and comfort leads to more milk output and fit starts with your flange.

What we  about it

Helps you find the just-right breast pump flange fit.

Details

  • Includes:
    • 13mm, 15mm, 17mm, 19mm, 21mm insert sets
    • Nipple Sizing Tool
    • Pump Sizing 101 Guide
    • 1:1 virtual visit with a Willow Sizing Specialist
  • Connect with a Sizing Specialist for personalized guidance
  • Use with any pump; they’re compatible with almost all 24mm flanges
  • Fit most nipple sizes

More to consider

Q&A

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Customer reviews

28 Ratings
4.9out of 5
28 Ratings

Rated 5 stars by 93% of reviewers

Rated 4 stars by 7% of reviewers

Rated 3 stars by 0% of reviewers

Rated 2 stars by 0% of reviewers

Rated 1 star by 0% of reviewers

1-10 of 28 Reviews
Rated 5 out of 5
Helpful convenient sizing kit
Very convenient to have one product that makes it easy to determine what size you are without having to buy and return multiple products until you find the correct fit.
Bree
Mar 14, 2026
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Rated 5 out of 5
Sizing Kit Review
The sizing inserts are perfect for getting the right flange size! They are super comfortable. The best part is having a variety of sizes to try. This helped find the perfect fit. I highly recommend this product!
Britney H.
Mar 3, 2026
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Rated 5 out of 5
Breast pump sizing kit
This is my third baby and I was making it priority the third time around to have the correct size met for me. This kit made it incredibly easy, wish I would’ve done it sooner. Great product!
Shawna
Mar 2, 2026
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Rated 5 out of 5
Such a handy kit!
This kit is so handy for a newly breastfeeding mom! My flange size changed throughout my first time breastfeeding so I anticipate that happening again with my second. It’ll be handy as I continue to breastfeed and need to adjust sizes. I also like having all the sizes in the kit so I can try out which one works best. I highly recommend this flange kit!
Savannah
Mar 1, 2026
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Rated 5 out of 5
Breast Pump Sizing Kit
This kit was so nice to have at the hospital when baby was born this week! The hospital didn't have my correct size available but luckily I brought this kit with me. The willow inserts are very comfortable as well!
Cassidy G.
Feb 27, 2026
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Rated 5 out of 5
Convenient & easy to understand
This is a great kit with easy instructions on how to size yourself . I love the material of the flanges and how the kit comes with several sizes
Shara C.
Feb 26, 2026
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Rated 4 out of 5
Made sizing easy
This sailing kit came with all the bells and whistles compared to others! Not only did I get the traditional paper sizing cut out but also flanges to trial. The kit included a 1:1 consult with a specialist which I thought was amazing! I now have my correct flange sizes and am excited to pump with them 🙂
Sofia M.
Feb 26, 2026
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Rated 5 out of 5
Great for beginners
Where was this 15 yrs ago when I was a new mom. After discovering Willow 3 yrs ago this new size box is perfect for any pump and any nursing mama! This is so easy to determine proper sizing. It works well considering all you need for that perfect size is all in 1 box! I highly recommend to anyone starting their breast feeding/pumping journey!
Nicole M.
Feb 25, 2026
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Rated 5 out of 5
Great for moms motivated to pump as long as possible!
Throughout my 1yr+ pumping journey I changed insert sizes 3 times! I love that these are flush with the flange. Sometimes unexpectedly you need to change your size and this helps you determine a good fit by trying at least 2 or 3 sizes to get the best comfort and output! Will definitely ease the stress of waiting days for a new size to come in the mail; if you already have this at home in your pump toolkit!
Quinn
Feb 25, 2026
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Rated 5 out of 5
Sizing kit is 10/10!!
There is nothing like Willow flanges. They fit perfectly in the Willow Go and corresponding pumps. They are the most comfortable I have ever tried. I never have an issue with pulling too hard or aggressively, the silicon is definitely the way to go with pumping. I love the diversity of sizing that comes with this pack, as my size changes during postpartum. When I had my first son I was originally a size 21, then went to 17 and back up to 19 to then pump for 15 months. I can’t wait to use this kit for my next pumping journey!!
Liz C.
Feb 25, 2026
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