Willow Sizing Insert Set Review: Do You Really Need It?
By Willow: Wearable Breast Pump – Willow Pump | Published: 2026-08-20
Category: Product Reviews
Wondering if the Willow Sizing Insert Set is worth it? Our review covers fit, comfort, and whether you need it for your Willow pump.
Getting the right fit with your wearable breast pump is one of the most important factors for both comfort and milk output. If you’re a Willow pump user, you’ve probably heard about the Willow Sizing Insert Set—a small accessory that promises to fine-tune the fit of your flanges. But do you actually need it? In this review, we’ll break down what the inserts do, who they’re for, and whether they’re a worthy addition to your pumping toolkit.
We’ll also compare the sizing inserts with other Willow accessories like the Willow Go® Flange Set and the Willow 360® Container Set, so you can make an informed decision. Whether you’re a first-time pump buyer or a seasoned pro looking to optimize your setup, this guide will help you decide if the Willow Sizing Insert Set is right for you.
What Is the Willow Sizing Insert Set?
The Willow Sizing Insert Set is a set of small, flexible inserts designed to adjust the internal diameter of your pump flange. By placing an insert inside the flange, you can effectively reduce the flange size without buying a whole new flange set. This is particularly useful if your nipple size falls between standard flange sizes or if you experience discomfort with the standard 21mm or 24mm options.
The inserts are made from soft, medical-grade silicone that conforms to your breast tissue, creating a gentle seal. They’re easy to insert and remove, and they can be cleaned along with your other pump parts. The set typically includes multiple sizes, allowing you to experiment and find the perfect fit for your unique anatomy.
- Adjusts flange size without buying new flanges
- Soft silicone for comfort and flexibility
- Multiple sizes included for a custom fit
- Easy to clean and maintain
Why Flange Fit Matters for Pumping Comfort and Output
Using the wrong flange size can lead to a host of problems, including nipple pain, chafing, and reduced milk output. When the flange is too large, your nipple may be pulled too far into the tunnel, causing friction and discomfort. If it’s too small, your nipple may rub against the sides, leading to soreness and even blocked ducts.
The Willow Sizing Insert Set helps you achieve a precise fit, which can improve both comfort and milk expression. A proper fit ensures that your nipple is centered and that the suction is distributed evenly, which can help you empty your breasts more effectively. For moms who pump frequently, this can make a significant difference in their overall pumping experience.
Who Should Consider the Willow Sizing Insert Set?
The Willow Sizing Insert Set is ideal for moms who fall between standard flange sizes. If you’ve ever measured your nipple and found that you’re between a 21mm and 24mm, for example, these inserts can bridge the gap. They’re also great for moms who experience nipple swelling during pumping, as the inserts can accommodate slight size changes.
Additionally, if you’ve noticed that your current flange size causes discomfort or doesn’t seem to be emptying your breasts fully, the inserts are a low-cost way to test a different size before committing to a new flange set. They’re also useful for moms who are using a Willow pump for the first time and want to ensure they get the best fit from the start.
How to Use the Willow Sizing Insert Set
Using the inserts is straightforward. Start by washing your hands and the inserts thoroughly. Then, place the insert inside the flange tunnel, ensuring it sits flush against the inner wall. Make sure it’s secure before attaching the flange to your breast. You can adjust the insert’s position as needed to achieve a comfortable seal.
It’s important to note that the inserts are designed to be used with specific Willow pump models. Always check compatibility with your pump before use. If you’re using a Willow Go® Pump, for example, you’ll want to ensure the inserts fit the Go flange. The inserts are also compatible with the Willow 360® system, but it’s always best to verify.
Comparing the Sizing Insert Set with Other Willow Accessories
The Willow Sizing Insert Set is just one of many accessories designed to enhance your pumping experience. For instance, the Willow Go® Pump and 7 oz Breast Milk Containers bundle offers a complete pumping solution with extra storage, while the Willow 360® Container Set (2-pack) provides additional containers for milk collection. These accessories serve different purposes, but they all contribute to a more convenient and comfortable pumping routine.

If you’re looking to improve fit, the sizing inserts are a must-have. However, if you’re also in need of extra storage or a backup pump, you might consider bundling your purchase. The Smart Storage Bundle combines storage solutions with other essentials, making it a great addition to your pumping arsenal.
Pros and Cons of the Willow Sizing Insert Set
Like any product, the Willow Sizing Insert Set has its advantages and potential drawbacks. Here’s a quick rundown to help you decide:
Pros: The inserts are affordable, easy to use, and can significantly improve comfort and milk output. They’re also a great way to test different sizes without buying multiple flange sets. Cons: They may not be necessary for moms who already have a perfect fit, and they add an extra piece to clean. Additionally, if you have very sensitive skin, you might need to ensure the silicone doesn’t cause irritation.
- Pros: Cost-effective, customizable fit, improved comfort
- Cons: Extra cleaning step, not needed if fit is already perfect
Final Verdict: Is the Willow Sizing Insert Set Worth It?
If you’re experiencing discomfort or suboptimal milk output due to flange fit, the Willow Sizing Insert Set is absolutely worth trying. It’s a low-cost, non-committal way to improve your pumping experience. Even if you’re not sure whether you need it, the inserts can be a valuable tool for fine-tuning your setup.
For moms who are happy with their current flange size, the inserts may be unnecessary. However, for those who are struggling with fit, they can be a game-changer. We recommend giving them a try if you’re on the fence—you might be surprised at the difference they make.
In summary, the Willow Sizing Insert Set is a practical accessory for any Willow pump user who wants to optimize fit and comfort. Whether you’re new to pumping or a seasoned pro, these inserts can help you achieve a better pumping experience. If you’re ready to improve your fit, check out the Willow Sizing Insert Set today and see the difference for yourself.



