How to Use Flange Inserts With Your Pump

You measured, you picked your size, and a tiny pack of silicone just landed on your doorstep. Nice work. Honestly, sizing is the hard part.

Now comes the part nobody explains very well: actually getting those inserts into your pump. Every pump is a little different, and the instructions tend to live in five different places.

So we put it all in one spot. Find your pump below to see how your inserts go in, then check what it should feel like so you know it worked.

Think of a flange insert as a soft sleeve that makes your breast shield's tunnel smaller. Lots of pumps come with larger standard shields, and bodies come in every size. Inserts close the gap so you can pump with a fit that feels right for you, without buying a whole new set of shields.

Legendairy Milk Flange Inserts come in a set of two and in five sizes: 13, 15, 17, 19 and 21 mm. They're made from phthalate-free, BPA-free, food-grade silicone.

They fit:

• Most traditional 24 and 25 mm hard plastic breast shields

• The 24 and 28 mm silicone breast shields that come with our Silicone Collection Cups

They don't fit:

• The 21 mm Silicone Collection Cups breast shields

• The Imani i2 and i2 Plus, which use their own Imani Inserts

Still deciding on your size, or want to double-check? Our guide on how to find your perfect flange size walks you through measuring.

Whatever pump you use, these two steps are the same. Then find your pump below for how your inserts go in.

1. Sterilize once

Before first use, fully submerge your inserts in a deep, wide pot of boiling water for 3 to 5 minutes. Keep them from touching the bottom or sides of the pot. This is a one-time thing. After that, skip the boiling and high heat.

2. Slide them in

Inserts are very soft and bendy, which is great for comfort and a little tricky for installing. Add a dab of Pumping Spray or coconut oil inside your hard plastic shield, then slide the insert into the tunnel.

First, check the size printed on your hard plastic shield. If it's 24 or 25 mm, your inserts slide right into the tunnel using the steps above. Then assemble your Spectra kit as usual.

Want a softer feel? Our 24 mm silicone breast shield from the Silicone Collection Cups can also work as a stand-alone flange on a Spectra, and your inserts fit inside it. You'll need the right connector, so read Silicone Breast Shield Hack: Medela and Spectra before you start.

Same first step: check the size on your shield. A 24 or 25 mm hard plastic shield takes your inserts using the steps above.

The silicone shield hack works with Medela connectors too, including the PersonalFit Flex. The full walkthrough is in Silicone Breast Shield Hack: Medela and Spectra.

Your inserts were designed with these in mind. Slide the insert into the 24 or 28 mm silicone breast shield, then assemble your cups as normal. Remember, they won't fit the 21 mm shields.

Need a refresher on the rest of the setup? See How to Assemble Legendairy Milk's Silicone Collection Cups.

The Imani i2 has its own Imani Inserts, sized 17, 19, 21 and 25 mm, made to fit right inside its shields. Our standard flange inserts aren't the match here. For the full setup, see How to Assemble Your Imani i2.

If your pump uses a traditional hard plastic shield marked 24 or 25 mm, your inserts should fit using the steps above. Not sure? Email us at info@legendairymilk.com with your pump model, and we'll help you figure it out.

Inserts in, pump on. Here's how to tell you got it right:

• Your nipple moves freely in the tunnel and touches the sides without pinching.

• Pumping feels comfortable, with no pain during or after.

• Your areola isn't being pulled far into the tunnel.

If something feels off, try one size up or down. Bodies change throughout your feeding journey, so it's worth rechecking every so often. And if pumping still hurts, reach out to a lactation professional or IBCLC. That's what they're there for.

Silicone is tough, but it's not invincible. A little care goes a long way:

• After every session: hand wash in warm, soapy water, then rinse clean.

• Air-dry completely: lay your inserts on a clean towel somewhere protected from dirt and dust, and leave them until they're fully dry. Skip rubbing or patting them dry, which can put germs right back on.

• Cold or UV sterilization: totally fine if that's part of your routine.

• Skip the dishwasher. Inserts aren't dishwasher safe.

• Skip the heat after day one. No re-boiling, no steam sterilizers, no high heat after that first sterilization.

For more cleaning shortcuts, see Washing Pump Parts: Tips + Hacks.

Replace your inserts every 3 weeks, depending on how often you pump. If you're pumping several times a day, they'll get more wear than if you're pumping one bottle for daycare.

And no matter how new they are, replace them right away if they become torn or damaged.

Pro tip: set a phone reminder the day you open a fresh pair. When it goes off, you'll already know it's time to restock.

My insert keeps slipping. What do I do?

Make sure it's pushed fully into the tunnel, and that your shield is 24 or 25 mm. A dab of Pumping Spray or coconut oil on the hard plastic helps it slide in and sit in place.

Can I use a different insert size on each side?

Yes. Lots of people measure a different size on each side, so it's worth measuring both separately.

Do inserts fit the 21 mm Silicone Collection Cups shields?

No. Inserts fit the 24 and 28 mm Collection Cups shields only.

Can I return inserts if the size isn't right?

Flange Inserts aren't returnable, so measure first. Our Flange Sizing Starter Kit includes a silicone nipple ruler and five insert sizes if you'd like to try a few before committing.

Getting the right fit can take a little trial and error, and that's completely normal. Once your inserts are in and feeling good, all that's left is a quick wash after each session and a fresh pair every few weeks.

You've got this. And if you get stuck, we're just an email away.

Shop the setup:

• Flange Inserts

• Flange Sizing Starter Kit

• Silicone Nipple Ruler

• Pumping Spray

• All Pumping Accessories