---
title: "21mm flange insert — Niche Verdict: Skip it (29/100) | Amazon United States - Flapen"
canonical_url: "https://flapen.com/amazon/research/us/baby-products/21mm-flange-insert"
last_updated: "2026-07-14T04:56:42.654Z"
locale: en
meta:
  description: "prices mostly outside the sweet spot ($6.92–$14.62) — 21mm flange insert doesn't clear our bar today."
  "og:description": "prices mostly outside the sweet spot ($6.92–$14.62) — 21mm flange insert doesn't clear our bar today."
  "og:title": "21mm flange insert — Niche Verdict: Skip it (29/100) | Amazon United States - Flapen"
---

Back to Flapen home

# **21mm flange insert**

**Skip it**

Prices mostly outside the sweet spot ($6.92–$14.62) — this niche doesn't clear our bar today.

Market size 13Growth 21Conversion 97Competition 6Returns 35Price range 0Avg price 27Brand share 19Review moat 49Quality gap 37

**Conversion**

**Incredible****14.6%**

search→purchase rate — share of searches ending in a sale

**Review moat**

**Okay****1,579.86**

avg incumbent reviews — the moat a new listing must climb

**Quality gap**

**Okay****4.5★**

avg incumbent rating — lower means beatable quality

**Returns**

**Okay****4.8%**

return rate — above 6% kills the launch gate

**Avg price**

**Okay****$9.27**

avg listing price — sweet spot $15–$100

**Growth**

**Bad****-7.5%**

90-day search growth — must beat 0% to launch

**Brand share**

**Bad****93%**

top-5 brand share — brand-locked demand

**Market size**

**Bad****$53K**

$53K/yr · 40K searches

**Competition**

**Bad****93%**

top-5 click share — a locked-up shelf

**Price range**

**Bad****$6.92–$14.62**

cheapest to priciest tracked listing — scored on the share inside $15–$100

## **Competition**

The top 5 products capture 93% of clicks — a locked-up shelf that new listings rarely crack.

**Brands**

**7 **▼falling

**Sellers**

**9**

**Top-5 brand share**

**93%**

**Open market**

**3%**

- Suniceme53% - Hranio24% - BDICOVE6% - GOCROWEEN6% - Maymom4% - Nuliie4% - Open — no brand owns it (1 brand, 3%)

## **Product shelf**

Each bubble is one product — market share against review moat; bubble size tracks estimated sales, color grades how beatable the incumbent looks.

0%15%$8K30%$16K45%$24K60%$32K1001K10K Reviews — right = deep review moatMarket share (90d) ≈ est. sales

Beatable (≤4.3★) Contested Strong incumbent (>4.7★)

All 7 tracked products in this niche — three views at once, no toggling.

### **Top sellers**

by 90-day click share

[1![Flange Inserts 21mm Compatible with Medela/Spectra/TSRETE/Elvie/Momcozy/Bellababy Breast Pump 24mm Shields/Flanges Reduce 24mm Nipple Tunnel Down to 21 mm 4PCS](https://m.media-amazon.com/images/I/31bhFe+EYtL.jpg)**Flange Inserts 21mm Compatible with Medela/Spectra/TSRETE/Elvie/Momcozy/Bellababy Breast Pump 24mm Shields/Flanges Reduce 24mm Nipple Tunnel Down to 21 mm 4PCS**Suniceme**$7.97**4.5★971 rev](https://www.amazon.com/dp/B0CW1VDP9D) [2![21mm Flange Insert 6PC Compatible with 21mm Flange Spectra/Flange Inserts for Spectra Flange 21mm/Momcozy Wearable Breast Pump Flange Insert/Medela Flange 21mm/Elvie/Willow/TSRETE](https://m.media-amazon.com/images/I/31J-aJBRo2L.jpg)**21mm Flange Insert 6PC Compatible with 21mm Flange Spectra/Flange Inserts for Spectra Flange 21mm/Momcozy Wearable Breast Pump Flange Insert/Medela Flange 21mm/Elvie/Willow/TSRETE**Hranio**$9.88**4.5★562 rev](https://www.amazon.com/dp/B0CL5MM4HH) [3![4Pcs Breast Pump Flange Insert 21mm Compatible with Momcozy/Spectra/Medela/eufy/Elvie/Lansinoh/Paruu P10 Breast Pump Fit for Momcozy M5/M9/M6/V2 Pro/V2 pro/S12 Pro/eufy E10 S1 S1 Pro 24mm Flange](https://m.media-amazon.com/images/I/41GmonptJBL.jpg)**4Pcs Breast Pump Flange Insert 21mm Compatible with Momcozy/Spectra/Medela/eufy/Elvie/Lansinoh/Paruu P10 Breast Pump Fit for Momcozy M5/M9/M6/V2 Pro/V2 pro/S12 Pro/eufy E10 S1 S1 Pro 24mm Flange**BDICOVE**$7.84**4.5★635 rev](https://www.amazon.com/dp/B0DS6YQGNT) [4![Flange Inserts 21mm 8PC Compatible with Momcozy S12 pro/S9 pro/S9/S10/S12/Medela/TSRETE/Spectra/Bellababy etc 24mm Wearable Breast Pump Reduce 24mm Tunnel Down to Correct Size](https://m.media-amazon.com/images/I/313cBDiZjrL.jpg)**Flange Inserts 21mm 8PC Compatible with Momcozy S12 pro/S9 pro/S9/S10/S12/Medela/TSRETE/Spectra/Bellababy etc 24mm Wearable Breast Pump Reduce 24mm Tunnel Down to Correct Size**GOCROWEEN**$7.96**4.6★347 rev](https://www.amazon.com/dp/B0CM5RB96P) [5![Maymom Flange 21mm Insert Compatible with Medela/Spectra/Elvie/momcozy/tsrete/Willow/Motif Luna/Ameda MYA Breastpump 24mm Breast Shields. Reduce 24mm Niple Tunnel Down to 21mm](https://m.media-amazon.com/images/I/21P7xLlZadL.jpg)**Maymom Flange 21mm Insert Compatible with Medela/Spectra/Elvie/momcozy/tsrete/Willow/Motif Luna/Ameda MYA Breastpump 24mm Breast Shields. Reduce 24mm Niple Tunnel Down to 21mm**Maymom**$14.62**4.5★3,517 rev](https://www.amazon.com/dp/B0BGXPQ6VS)

**~~View all top sellers →~~**

### **Newest**

by launch date

[![4Pcs Breast Pump Flange Insert 21mm Compatible with Momcozy/Spectra/Medela/eufy/Elvie/Lansinoh/Paruu P10 Breast Pump Fit for Momcozy M5/M9/M6/V2 Pro/V2 pro/S12 Pro/eufy E10 S1 S1 Pro 24mm Flange](https://m.media-amazon.com/images/I/41GmonptJBL.jpg)**4Pcs Breast Pump Flange Insert 21mm Compatible with Momcozy/Spectra/Medela/eufy/Elvie/Lansinoh/Paruu P10 Breast Pump Fit for Momcozy M5/M9/M6/V2 Pro/V2 pro/S12 Pro/eufy E10 S1 S1 Pro 24mm Flange**BDICOVE**$7.84**635 rev1y ago](https://www.amazon.com/dp/B0DS6YQGNT) [![IVARONAL Flange Insert 2PCS 21mm Compatible with Momcozy M9/M6/M5/S12 Pro/V1 Pro/V2 pro Spectra/Medela/Elvie/NCVI/TSRETE/eufy/Lansinoh/Paruu/MomMed Breast Pump 24mm Shields/Flanges (2pcs-21mm)](https://m.media-amazon.com/images/I/31dfYRIa3sL.jpg)**IVARONAL Flange Insert 2PCS 21mm Compatible with Momcozy M9/M6/M5/S12 Pro/V1 Pro/V2 pro Spectra/Medela/Elvie/NCVI/TSRETE/eufy/Lansinoh/Paruu/MomMed Breast Pump 24mm Shields/Flanges (2pcs-21mm)**IVARONAL**$6.92**848 rev2y ago](https://www.amazon.com/dp/B0D4DMXGJ1) [![Flange Inserts 21mm Compatible with Medela/Spectra/TSRETE/Elvie/Momcozy/Bellababy Breast Pump 24mm Shields/Flanges Reduce 24mm Nipple Tunnel Down to 21 mm 4PCS](https://m.media-amazon.com/images/I/31bhFe+EYtL.jpg)**Flange Inserts 21mm Compatible with Medela/Spectra/TSRETE/Elvie/Momcozy/Bellababy Breast Pump 24mm Shields/Flanges Reduce 24mm Nipple Tunnel Down to 21 mm 4PCS**Suniceme**$7.97**971 rev2y ago](https://www.amazon.com/dp/B0CW1VDP9D) [![Nuliie 3-in-1 Flange Sizing Kit 13/15/17/19/21mm for 24mm Electric Double Breast Pump Flange/Shield 10PCS Silicone Flange Inserts to Boost Pumping Efficiency & Comfort BPA-Free Essential for Moms](https://m.media-amazon.com/images/I/41Feyi97wML.jpg)**Nuliie 3-in-1 Flange Sizing Kit 13/15/17/19/21mm for 24mm Electric Double Breast Pump Flange/Shield 10PCS Silicone Flange Inserts to Boost Pumping Efficiency & Comfort BPA-Free Essential for Moms**Nuliie**$9.68**4,179 rev2y ago](https://www.amazon.com/dp/B0CMPBBHMZ) [![21mm Flange Insert 6PC Compatible with 21mm Flange Spectra/Flange Inserts for Spectra Flange 21mm/Momcozy Wearable Breast Pump Flange Insert/Medela Flange 21mm/Elvie/Willow/TSRETE](https://m.media-amazon.com/images/I/31J-aJBRo2L.jpg)**21mm Flange Insert 6PC Compatible with 21mm Flange Spectra/Flange Inserts for Spectra Flange 21mm/Momcozy Wearable Breast Pump Flange Insert/Medela Flange 21mm/Elvie/Willow/TSRETE**Hranio**$9.88**562 rev2y ago](https://www.amazon.com/dp/B0CL5MM4HH)

**~~View all new products →~~**

### **Trending**

90-day click momentum

[![Flange Inserts 21mm 8PC Compatible with Momcozy S12 pro/S9 pro/S9/S10/S12/Medela/TSRETE/Spectra/Bellababy etc 24mm Wearable Breast Pump Reduce 24mm Tunnel Down to Correct Size](https://m.media-amazon.com/images/I/313cBDiZjrL.jpg)**Flange Inserts 21mm 8PC Compatible with Momcozy S12 pro/S9 pro/S9/S10/S12/Medela/TSRETE/Spectra/Bellababy etc 24mm Wearable Breast Pump Reduce 24mm Tunnel Down to Correct Size**GOCROWEEN**$7.96**4.6★**▲ 143%**](https://www.amazon.com/dp/B0CM5RB96P) [![4Pcs Breast Pump Flange Insert 21mm Compatible with Momcozy/Spectra/Medela/eufy/Elvie/Lansinoh/Paruu P10 Breast Pump Fit for Momcozy M5/M9/M6/V2 Pro/V2 pro/S12 Pro/eufy E10 S1 S1 Pro 24mm Flange](https://m.media-amazon.com/images/I/41GmonptJBL.jpg)**4Pcs Breast Pump Flange Insert 21mm Compatible with Momcozy/Spectra/Medela/eufy/Elvie/Lansinoh/Paruu P10 Breast Pump Fit for Momcozy M5/M9/M6/V2 Pro/V2 pro/S12 Pro/eufy E10 S1 S1 Pro 24mm Flange**BDICOVE**$7.84**4.5★**▲ 88%**](https://www.amazon.com/dp/B0DS6YQGNT) [![Nuliie 3-in-1 Flange Sizing Kit 13/15/17/19/21mm for 24mm Electric Double Breast Pump Flange/Shield 10PCS Silicone Flange Inserts to Boost Pumping Efficiency & Comfort BPA-Free Essential for Moms](https://m.media-amazon.com/images/I/41Feyi97wML.jpg)**Nuliie 3-in-1 Flange Sizing Kit 13/15/17/19/21mm for 24mm Electric Double Breast Pump Flange/Shield 10PCS Silicone Flange Inserts to Boost Pumping Efficiency & Comfort BPA-Free Essential for Moms**Nuliie**$9.68**4.6★**▲ 18%**](https://www.amazon.com/dp/B0CMPBBHMZ) [![21mm Flange Insert 6PC Compatible with 21mm Flange Spectra/Flange Inserts for Spectra Flange 21mm/Momcozy Wearable Breast Pump Flange Insert/Medela Flange 21mm/Elvie/Willow/TSRETE](https://m.media-amazon.com/images/I/31J-aJBRo2L.jpg)**21mm Flange Insert 6PC Compatible with 21mm Flange Spectra/Flange Inserts for Spectra Flange 21mm/Momcozy Wearable Breast Pump Flange Insert/Medela Flange 21mm/Elvie/Willow/TSRETE**Hranio**$9.88**4.5★**— 4%**](https://www.amazon.com/dp/B0CL5MM4HH) [![Flange Inserts 21mm Compatible with Medela/Spectra/TSRETE/Elvie/Momcozy/Bellababy Breast Pump 24mm Shields/Flanges Reduce 24mm Nipple Tunnel Down to 21 mm 4PCS](https://m.media-amazon.com/images/I/31bhFe+EYtL.jpg)**Flange Inserts 21mm Compatible with Medela/Spectra/TSRETE/Elvie/Momcozy/Bellababy Breast Pump 24mm Shields/Flanges Reduce 24mm Nipple Tunnel Down to 21 mm 4PCS**Suniceme**$7.97**4.5★**— 6%**](https://www.amazon.com/dp/B0CW1VDP9D)

**~~View all trending →~~**

## **Demand & seasonality**

Weekly Amazon search volume, last 104 weeks — -7.5% search growth over the last 90 days.

1K600Spike '25Spike '26 seasonSepDecMarJunAugNovMarMay

No pronounced peak months · busiest ÷ quietest = 1.4×

## **Reviews**

What buyers praise and complain about, mined from review topics.

### **What buyers love **

**Size-Overall**26%

*“The best sizing kit”*

**Quality-Overall**17%

*“One thing that really stood out to me was how well-made”*

**Value For Money**9%

*“Great price”*

**Comfort-Overall**7%

*“are very comfy”*

**Ease Of Cleaning**7%

*“The little cleaning sponge is wonderful”*

**Ease Of Use**6%

*“Easy to use”*

**Advertised Vs Actual Product**5%

*“It performs exactly as intended”*

**Breastfeeding Friendly**4%

*“Very helpful and useful for breastfeeding”*

**Durability**3%

*“durable”*

**Compatibility-Overall**2%

*“Compatible with spectra pumps”*

### **What buyers complain about **

**Size-Overall**25%

*“Not true size”*

**Quality-Overall**8%

*“Poor quality”*

**Durability**5%

*“one of the flange inserts tore right apart immediately after opening”*

**Value For Money**5%

*“Waste of money”*

**Comfort-Overall**5%

*“Not comfortable”*

**Skin Health**5%

*“Burned my skin”*

**Ease Of Use**4%

*“It makes the arduous”*

**Hard Feel**4%

*“the material is not as soft”*

**Material Quality**4%

*“Material hurts”*

**Adhesion/Stickiness**3%

*“Too sticky; nipple can move”*

### **Top return reasons **

**Size-Overall**61%

**Functionality-Overall**7%

**Advertised Vs Actual Product**6%

**Material Quality**4%

**Defective Material/Parts**4%

**Value For Money**3%

**Breastfeeding Friendly**2%

**Comfort-Overall**2%

**Width**2%

**Compatibility-Overall**2%