The Momcozy S12 Pro takes the Momcozy duckbill valve and diaphragm set for S9 Pro and S12 Pro (part MCMWX20-NA00NB-RT) as its valve; replace it every 3 months; Australian sellers list it from A$8.50 each as of 28 October 2026. Fitment confirmed against the manufacturer's compatibility list.
Your breast pump
Momcozy S12 Pro
Breast pump
Confirmed against Momcozy's listConfirmed against Momcozy's own compatibility list
Not yours? ChangeSave it · remind me every 3 months
Takes the MCMWX20-NA00NB-RT valve
duckbill valve and diaphragm set for S9 Pro and S12 Pro · replace every 3 months · check the code on your old part before ordering.
Your breast pump
Breast pump
Confirmed against Momcozy's listConfirmed against Momcozy's own compatibility list
Takes the MCMWX20-NA00NB-RT
Valve · every 3 months · check the code on your old part.
Other Momcozy breast pumps that take the MCMWX20-NA00NB-RT
GenuineGenuine Momcozy
$18.99
Amazon AU · 28 OctLowest genuine · Amazon AU · checked 28 Oct
CompatibleCompatible option
$8.50 each
2-pack $16.99
Amazon AU · 28 OctAmazon AU · checked 28 Oct
Check sellerCheck seller details
Genuine: made by Momcozy. Compatible: another brand.Genuine is made by Momcozy. Compatible is made by another brand. Check the seller's page for the size and models it fits.
Lowest compatibleLowest compatible price · $8.50 each · 2-pack $16.99
Amazon AU. Compare with genuine below. Some links earn us a commission. Some seller links earn us a commission, at no extra cost to you.
This breast pump also takes a backflow protector
- Momcozy linker for S9 Pro and S12 ProOpen Momcozy Australia$19.99
Separate from the valve. Replace every 6 months.
Compare 3 listings from 2 sellers
AUD, before delivery. Each price shows when it was checked.
Compatible options
1 seller
Opens Amazon AU in a new tab. Their page is the source of truth for price, delivery and returns.
Not due yet?
Get a nudge when your valve is due — it's every 3 months. One email two weeks before, no newsletter. Manage or stop it anytime.
How to change the valve in your Momcozy S12 Pro
Watch the guide or follow the steps.
- 1Wash your hands, take the pump off and separate the milk collector, flange and silicone parts.
- 2Remove the old duckbill valve and diaphragm and check the other silicone parts for cracks, tears or stretching.
- 3Before first use, wash the new duckbill valve and diaphragm and boil it for 5 to 10 minutes, then let it air dry.
- 4Fit the new duckbill valve and diaphragm in the same place as the old one, so it sits snugly and lies flat.
- 5Reassemble the pump and check for leaks or low suction before pumping.
Every number this part goes by
- Retail name:
- MCMWX20
- Retail name:
- MCMWX20-NA00NB-RT
- Retail name:
- Momcozy S12 Pro diaphragm
- Retail name:
- Momcozy S12 Pro duckbill valve
- Retail name:
- Momcozy S9 Pro diaphragm
- Retail name:
- Momcozy S9 Pro duckbill valve
Sellers list any of these; they are the same part.
About your Momcozy S12 Pro
Momcozy breast pump — S series. Its valve is the duckbill valve and diaphragm set for S9 Pro and S12 Pro, part MCMWX20-NA00NB-RT, changed every 3 months.
Also in this breast pump: Momcozy linker for S9 Pro and S12 Pro (every 6 months).
Where the model number is: The model name is printed on the motor unit or its base, and on the box. Wearable pumps also show it in the maker's app.
Common questions
- Which valve fits the Momcozy S12 Pro?
- The Momcozy S12 Pro takes the Momcozy duckbill valve and diaphragm set for S9 Pro and S12 Pro (part MCMWX20-NA00NB-RT).
- How often should I replace the valve in my Momcozy S12 Pro?
- Every 3 months, or sooner if it looks worn.
- Where can I buy the MCMWX20-NA00NB-RT in Australia?
- We track 2 Australian sellers for the MCMWX20-NA00NB-RT; the lowest listed price when we last checked was A$8.50 at Amazon AU. Prices are re-checked daily and dated on this page.
- How do I fit the MCMWX20-NA00NB-RT in a Momcozy S12 Pro?
- No tools, a few minutes: 5 steps, listed on this page with the replacement video where the maker has one.
- What happens if I don't change it?
- A stretched or torn valve or membrane lets the suction drop, so each session takes longer.
- Is there anything to reset afterwards?
- No reset: the pump has no reminder for this part, so set your own.
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