---
title: "3/8 check valve — Niche Verdict: Skip it (46/100) | Amazon United States - Flapen"
canonical_url: "https://flapen.com/amazon/research/us/automotive/3-8-check-valve"
last_updated: "2026-07-14T04:24:15.850Z"
locale: en
meta:
  description: "a small market ($61K/yr) — 3/8 check valve doesn't clear our bar today."
  "og:description": "a small market ($61K/yr) — 3/8 check valve doesn't clear our bar today."
  "og:title": "3/8 check valve — Niche Verdict: Skip it (46/100) | Amazon United States - Flapen"
---

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# **3/8 check valve**

**Skip it**

A small market ($61K/yr) — this niche doesn't clear our bar today.

Market size 15Growth 33Conversion 77Competition 34Returns 65Price range 69Avg price 62Brand share 34Review moat 66Quality gap 67

**Conversion**

**Great****7.5%**

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

**Price range**

**Good****$6.18–$34.84**

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

**Quality gap**

**Good****4.3★**

avg incumbent rating — lower means beatable quality

**Review moat**

**Good****864.17**

avg incumbent reviews — the moat a new listing must climb

**Returns**

**Good****2.4%**

return rate — above 6% kills the launch gate

**Avg price**

**Good****$13.41**

avg listing price — sweet spot $15–$100

**Competition**

**Okay****65%**

top-5 click share — leaders hold, buyers still browse

**Brand share**

**Okay****85%**

top-5 brand share — brands hold most of the demand

**Growth**

**Okay****+6.3%**

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

**Market size**

**Bad****$61K**

$61K/yr · 60K searches

## **Competition**

The top 5 products take 65% of clicks — established leaders, but buyers still shop beyond them.

**Brands**

**11 **▼falling

**Sellers**

**42**

**Top-5 brand share**

**85%**

**Open market**

**12%**

- EVIL ENERGY55% - mxuteuk10% - Litoexpe9% - Tandefio7% - BBTUS3% - ChillWaves3% - Open — no brand owns it (5 brands, 12%)

## **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%10%$6K20%$12K30%$18K40%$24K101001K10K Reviews — right = deep review moatMarket share (90d) ≈ est. sales

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

All 18 tracked products in this niche — three views at once, no toggling.

### **Top sellers**

by 90-day click share

[1![EVIL ENERGY 3/8 Fuel Check Valve One Way Inline Non Return Diesel Gasoline Black (10mm OD 2PCS)](https://m.media-amazon.com/images/I/41HHubT0yTL.jpg)**EVIL ENERGY 3/8 Fuel Check Valve One Way Inline Non Return Diesel Gasoline Black (10mm OD 2PCS)**EVIL ENERGY**$13.03**4.5★3,115 rev](https://www.amazon.com/dp/B08JJ1F79D) [2![Litoexpe 3/8 One Way Inline Check Valve Non Return Ozone Resistance PVDF Plastic One-Way Fuel Oil Water Gas Pump Air Check Valve Pack of 2](https://m.media-amazon.com/images/I/21IIesZQ+LL.jpg)**Litoexpe 3/8 One Way Inline Check Valve Non Return Ozone Resistance PVDF Plastic One-Way Fuel Oil Water Gas Pump Air Check Valve Pack of 2**Litoexpe**$6.18**4.1★254 rev](https://www.amazon.com/dp/B0BBLY454S) [3![mxuteuk 2Pcs 3/8 10mm Aluminium Silver Non Return One Way Check Valve with 4Pcs 6-12mm Universal Adjustable Hose Clamps for Fuel Petrol Diesel Line Oil M-H-032-10mm](https://m.media-amazon.com/images/I/41of1kEegoL.jpg)**mxuteuk 2Pcs 3/8 10mm Aluminium Silver Non Return One Way Check Valve with 4Pcs 6-12mm Universal Adjustable Hose Clamps for Fuel Petrol Diesel Line Oil M-H-032-10mm**mxuteuk**$9.04**4.4★396 rev](https://www.amazon.com/dp/B09C7S53X8) [4![Tandefio 4 Pcs 1/4 5/16 3/8 1/2 Fuel Non Return Inline One Way Check Valve for Fuel Line Oil Petrol Diesel Gasoline Water Aluminium Alloy Silver 6 mm 8 mm 10 mm 12 mm](https://m.media-amazon.com/images/I/41WuCnvpi6L.jpg)**Tandefio 4 Pcs 1/4 5/16 3/8 1/2 Fuel Non Return Inline One Way Check Valve for Fuel Line Oil Petrol Diesel Gasoline Water Aluminium Alloy Silver 6 mm 8 mm 10 mm 12 mm**Tandefio**$10.18**4.1★140 rev](https://www.amazon.com/dp/B0CP2DPNPJ) [5![EVIL ENERGY 5/16 Fuel Check Valve One Way Inline Non Return Diesel Gasoline Silver (8mm OD 2PCS)](https://m.media-amazon.com/images/I/41UFGe80Y0L.jpg)**EVIL ENERGY 5/16 Fuel Check Valve One Way Inline Non Return Diesel Gasoline Silver (8mm OD 2PCS)**EVIL ENERGY**$9.98**4.5★3,115 rev](https://www.amazon.com/dp/B07ZB42CGT)

**~~View all top sellers →~~**

### **Newest**

by launch date

[![mxuteuk 2Pcs 3/8 10mm Aluminium Black Non Return One Way Check Valve with 4Pcs 6-12mm Universal Adjustable Hose Clamps for Fuel Petrol Diesel Line Oil](https://m.media-amazon.com/images/I/41BqqAhziGL.jpg)**mxuteuk 2Pcs 3/8 10mm Aluminium Black Non Return One Way Check Valve with 4Pcs 6-12mm Universal Adjustable Hose Clamps for Fuel Petrol Diesel Line Oil**mxuteuk**$9.68**396 rev6mo ago](https://www.amazon.com/dp/B0GCM68KYT) [![EVIL ENERGY 3/8 (10mm) Check Valve 2 Pcs Aluminum One Way Fuel Check Valve for Gasoline Diesel & Coolant with Universal Hose Clamps Silver](https://m.media-amazon.com/images/I/410BGPUazSL.jpg)**EVIL ENERGY 3/8 (10mm) Check Valve 2 Pcs Aluminum One Way Fuel Check Valve for Gasoline Diesel & Coolant with Universal Hose Clamps Silver**EVIL ENERGY**$13.33**43 rev7mo ago](https://www.amazon.com/dp/B0FQHCJ1NH) [![EVIL ENERGY 3/8 (10mm) Check Valve 2 Pcs Aluminum One Way Fuel Check Valve for Gasoline Diesel & Coolant with Universal Hose Clamps Black](https://m.media-amazon.com/images/I/41F26MJP6GL.jpg)**EVIL ENERGY 3/8 (10mm) Check Valve 2 Pcs Aluminum One Way Fuel Check Valve for Gasoline Diesel & Coolant with Universal Hose Clamps Black**EVIL ENERGY**$13.86**43 rev8mo ago](https://www.amazon.com/dp/B0FQJ6NJLN) [![GASHER 1Pc One-Way Non-return Check Valve 3/8 Male x 3/8 Female Thread Prevent Water Back-flow](https://m.media-amazon.com/images/I/31HFn+99iML.jpg)**GASHER 1Pc One-Way Non-return Check Valve 3/8 Male x 3/8 Female Thread Prevent Water Back-flow**GASHER**$10.24**15 rev9mo ago](https://www.amazon.com/dp/B0FV2H27WR) [![ChillWaves 304 Stainless Steel In-Line Siamese Check Valve 3/8 NPT Male x 3/8 NPT Female Thread One-Way Non-return Check Valve for Backflow Prevention(1-PACK)](https://m.media-amazon.com/images/I/3198iCsW4NL.jpg)**ChillWaves 304 Stainless Steel In-Line Siamese Check Valve 3/8 NPT Male x 3/8 NPT Female Thread One-Way Non-return Check Valve for Backflow Prevention(1-PACK)**ChillWaves**$16.18**122 rev1y ago](https://www.amazon.com/dp/B0DPL9QD2C)

**~~View all new products →~~**

### **Trending**

90-day click momentum

[![mxuteuk 2Pcs 3/8 10mm Aluminium Black Non Return One Way Check Valve with 4Pcs 6-12mm Universal Adjustable Hose Clamps for Fuel Petrol Diesel Line Oil](https://m.media-amazon.com/images/I/41BqqAhziGL.jpg)**mxuteuk 2Pcs 3/8 10mm Aluminium Black Non Return One Way Check Valve with 4Pcs 6-12mm Universal Adjustable Hose Clamps for Fuel Petrol Diesel Line Oil**mxuteuk**$9.68**4.4★**▲ 179%**](https://www.amazon.com/dp/B0GCM68KYT) [![EVIL ENERGY 3/8 (10mm) Check Valve 2 Pcs Aluminum One Way Fuel Check Valve for Gasoline Diesel & Coolant with Universal Hose Clamps Silver](https://m.media-amazon.com/images/I/410BGPUazSL.jpg)**EVIL ENERGY 3/8 (10mm) Check Valve 2 Pcs Aluminum One Way Fuel Check Valve for Gasoline Diesel & Coolant with Universal Hose Clamps Silver**EVIL ENERGY**$13.33**4.4★**▲ 131%**](https://www.amazon.com/dp/B0FQHCJ1NH) [![GASHER 1Pc One-Way Non-return Check Valve 3/8 Male x 3/8 Female Thread Prevent Water Back-flow](https://m.media-amazon.com/images/I/31HFn+99iML.jpg)**GASHER 1Pc One-Way Non-return Check Valve 3/8 Male x 3/8 Female Thread Prevent Water Back-flow**GASHER**$10.24**4.4★**▲ 126%**](https://www.amazon.com/dp/B0FV2H27WR) [![EVIL ENERGY 5/16 Fuel Check Valve One Way Inline Non Return Diesel Gasoline Black (8mm OD 2PCS)](https://m.media-amazon.com/images/I/41TFH4wH8yL.jpg)**EVIL ENERGY 5/16 Fuel Check Valve One Way Inline Non Return Diesel Gasoline Black (8mm OD 2PCS)**EVIL ENERGY**$10.62**4.5★**▲ 97%**](https://www.amazon.com/dp/B08JJ128LN) [![EVIL ENERGY 3/8 (10mm) Check Valve 2 Pcs Aluminum One Way Fuel Check Valve for Gasoline Diesel & Coolant with Universal Hose Clamps Black](https://m.media-amazon.com/images/I/41F26MJP6GL.jpg)**EVIL ENERGY 3/8 (10mm) Check Valve 2 Pcs Aluminum One Way Fuel Check Valve for Gasoline Diesel & Coolant with Universal Hose Clamps Black**EVIL ENERGY**$13.86**4.4★**▲ 23%**](https://www.amazon.com/dp/B0FQJ6NJLN)

**~~View all trending →~~**

## **Demand**

Weekly Amazon search volume, last 14 weeks — +6.3% search growth over the last 90 days.

1K750Apr '26Apr '26May '26May '26May '26Jun '26Jun '26

## **Reviews**

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

### **What buyers love **

**Quality-Overall**27%

*“great variety”*

**Advertised Vs Actual Product**19%

*“works as it should”*

**Pressure**7%

*“Good check valve”*

**Value For Money**7%

*“But theyre cheap”*

**Efficiency**6%

*“Does the job”*

**Functionality-Overall**5%

*“The coffee maker is now working perfectly again”*

**Size-Overall**5%

*“fit”*

**Leak-Proof**3%

*“No leaks”*

**Assembly/Installation**3%

*“Easy to install”*

**Material Quality**2%

*“are made of high quality aluminum”*

### **What buyers complain about **

**Leak-Proof**20%

*“both of them leak after building pressure”*

**Pressure**11%

*“Doesnt hold pressure”*

**Quality-Overall**10%

*“Too cheap”*

**Functionality-Overall**9%

*“they are still not working”*

**Durability**7%

*“when i beat one it cracked”*

**Size-Overall**6%

*“3/8 hose is too large for these”*

**Fuel Efficiency**4%

*“blocks fuel flow”*

**Measurement/Reading Accuracy**4%

*“not lots of margin for error Working for over a months so far”*

**Strength**4%

*“Not robust”*

**Value For Money**4%

*“Wasted $33.31 for this”*

### **Top return reasons **

**Size-Overall**69%

**Advertised Vs Actual Product**8%

**Functionality-Overall**7%

**Pressure**3%

**Compatibility-Overall**3%

**Defective Material/Parts**3%

**Leak-Proof**2%

**Fuel Efficiency**1%

**Adhesion/Stickiness**1%

**Quality-Overall**1%