Willow Sizing Insert Set: How to Get the Perfect Flange Fit

Quick Answer

To get the perfect flange fit with Willow, use the sizing insert set to adjust the flange tunnel diameter so your nipple fits comfortably without excessive areola pull. Measure your nipple diameter, choose the insert size that matches, and place it securely before each pumping session.

A comfortable flange fit is the foundation of an efficient, pain-free pumping session. When the flange is too large, your nipple can swell and rub; when it's too small, milk flow can be restricted. The Willow sizing insert set helps you customize the fit so you can pump comfortably and effectively.

This guide walks you through measuring, selecting, inserting, and maintaining your Willow sizing inserts, so you can get the most out of every pumping session.

Why Flange Fit Matters

The right flange size ensures that your nipple is centered and can move freely without excessive friction. A poor fit can lead to discomfort, reduced milk output, and even skin irritation. With Willow's wearable pumps, a proper seal is also essential to prevent leaks and maintain the vacuum needed for efficient expression.

Many moms assume that one size fits all, but nipple size can change over time and even between sessions. That's why a sizing insert set is a smart investment—it lets you adjust the fit as needed without buying a whole new flange.

• Check your nipple size regularly, especially in the early weeks of breastfeeding.
• A good fit means your nipple moves freely but the surrounding areola is not pulled in excessively.

How to Choose the Right Insert Size

Start by measuring your nipple diameter. You can do this with a ruler or a printable sizing guide. Measure at the base of the nipple, not the tip. Then, compare your measurement to the sizes available in the Willow sizing insert set. If you're between sizes, it's usually better to size up to avoid pinching.

Keep in mind that your nipple size can change with letdown, so you may need to adjust the insert size during a session if you feel discomfort. The inserts are easy to swap, so you can experiment to find the most comfortable option.

• Measure both nipples—they may be different sizes.
• If you notice your nipple rubbing against the sides of the flange, try a smaller insert.

How to Use the Willow Sizing Insert Set

Using the inserts is straightforward. First, ensure your hands and the insert are clean. Then, place the insert inside the flange, pressing it firmly so it sits flush against the back. The insert should not obstruct the milk flow path. After placing the insert, position the pump as you normally would.

Check that your nipple is centered and that the insert creates a gentle seal. If you feel any pinching or if milk is pooling, adjust the insert or try a different size. After pumping, remove the insert and clean it according to the manufacturer's instructions.

Remember that inserts are consumable parts and should be replaced regularly to maintain hygiene and performance. The Willow brand recommends replacing pump parts every 90 days for optimal output.

• Always check for a secure fit before starting your session.
• If you notice a change in suction or comfort, inspect the insert for wear or damage.

Step-by-Step: Perfect Your Flange Fit with Willow Sizing Inserts

1. Measure Your Nipple Diameter: Use a ruler or a sizing card to measure the diameter of your nipple at the base. Do this when your nipple is at rest, not during letdown. Accuracy here prevents the most common fit mistakes.
2. Select the Correct Insert Size: Compare your measurement to the insert sizes in the Willow sizing insert set. If you are between sizes, choose the larger size for comfort. A common mistake is choosing too small—this can cause pinching.
3. Insert the Sizing Insert into the Flange: With clean hands, place the insert into the flange, pressing it firmly so it sits flat and does not block the milk flow path. Check that the insert is secure; a loose insert can break the seal.
4. Position the Pump and Check Fit: Place the pump in your bra, ensuring your nipple is centered in the flange. Start pumping and notice any discomfort or slipping. If you feel pinching, stop and adjust or try a different size.
5. Clean and Replace Inserts Regularly: After each use, remove the insert and wash it with warm soapy water. Inspect for wear and replace every 90 days or when you notice signs of wear. Regular replacement keeps your pump hygienic and effective.

Willow Products That Support a Good Fit

• Willow Sync Flange Set 24mm (2-pack): Replacing Your Parts For optimal output, replace every 90 days (or when you notice discomfort or signs of wear). Even with the right insert, a worn flange can cause leaks and discomfort. Replacing your flange set every 90 days helps maintain a consistent fit and performance.
• Willow Go® Container Duckbill Valve Set (2-pack): Willow Go's food-grade silicone valves keep your milk flowing in the right direction. Replace your parts regularly for optimal pumping performance. A properly functioning duckbill valve ensures efficient milk flow and prevents backflow, which is essential when you're using sizing inserts to optimize fit.

Achieving the perfect flange fit doesn't have to be a guessing game. With the Willow sizing insert set, you can fine-tune your pump to fit your body, making every session more comfortable and efficient. Remember to measure, choose, and place carefully—and to replace your inserts and other pump parts regularly to keep everything working at its best.