Best Adapter Fitting Nuts in 2026
Daisy
Last Updated: Feb 9, 2026
Daisy
Last Updated: Feb 9, 2026
* PickSmartly editors independently research, review, and endorse the top products through comprehensive data analysis. We may earn a commission for qualifying purchases made through our product links.
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| honest-f | 9.84 | ❌ | ❌ | ❌ |
Type: Compression Union
Tube Size:3/8" OD
Materies: BRASS
Net Weight: 34.7g/PC
Choosing products dimensions and quantities at column of size and colour seperately,price would be more favorable if choosing wholesale.
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| Fiada US | 9.93 | ✅ | ✅ | ✅ |
Fit for: the unions measures approx. 0.6 x 0.9 inch, the nut measures approx. 0.67 x 3/8 inch, fit for most common inverted flare or double flare sizes for 3/16 inch tube, for use with 3/16 inch steel, poly coated or copper brake lines; Please confirm the size of the details according to the picture before purchasing
Size and material: both the unions and nuts are metric 3/8-24 threads (regular 3/16 inch tube fitting size), all brake line fittings are made of quality brass to prevent rust and plated for corrosion resistance
You will get: 12 pieces brake line fittings in the package, include 4 pieces unions and 8 pieces nuts, you can share them with your family and friends, these tubes unions are good fittings
Inverted flare union: these unions are a nice option to join 2 (3/16 inch) brake lines together
Brake line fitting connect: the nut is called the fitting for 3/16 inch tube, these unions fittings have a hex size of 3/8 inch and the threads are 3/8 inch with a thread pitch of 24
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| Amazon.com | 9.68 | ✅ | ✅ | ✅ |
Three piece construction - nut, sleeve and body with attached insert
Use with copper, brass, aluminum, or plastic tubing
Standard fittings use short nuts
Easy to disassemble no flaring tool required
Primary uses water, gasoline, oil and vacuum lines
These fittings contain lead and are not allowed by federal law to be installed for potable water use in the U.S.A. and its territories.
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| ❌ | ❌ | ❌ |
★ 【Material】: Solid Brass construction. Durable Brass for corrosion resistance, ductility at high temperatures, and low magnetic permeability.
★ 【SIZE】: 3/8" Hose Barb x 3/8" Hose Barb.Thru-Bulk Bulkhead Fittings is connect with 3/8" ID hose with the same size.
★ 【Introduction】: Smooth surface and inner wall, durable Light and Small. Exquisite craftsman makes it safe and reliable.Bulkhead union coupling for connecting two hoses with the same diameter in a straight run.Barbed fitting for a tight seal on hoses.
★ 【Applications】: The fittings are fixed with 2 Gaskets and 1 fixed six corner, 1 movable six corner nuts form bulkhead tank function.Wide range of use: suitable for applications in water,fuel,air and etc.
★ 【Package Include】: 4 Pack 3/8" to 3/8" hose barb.It comes with 1 year warranty.
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| MuHize® Direct | 9.85 | ✅ | ✅ | ✅ |
PACKAGE INCLUDE - MuHize upgraded Brake Line Fittings Replacement (Pack of 15): ① 5 x 3/8-24 threads unions; ② 10 x 3/8-24 threads nuts. Note：Both the unions and nuts are 3/8-24 threads (regular 3/16 inch tube fitting size). Please check before shopping!
INVERTED FLARE UNION- Any 2 (3/16 inch) brake lines can be easy to joined with Muhize unions. both the sizes for unions and nuts are both 3/8-24 threads, which is the regular fitting size for 3/16 inch tube.
HIGHER QUALITY - MuHize brake line fittings are made of durable brass with unique rust corrosion proofing technology.
WIDELY APPLICATION - MuHize 3/8' - 24 threads fittings commonly fits for regular inverted flare/ double flare sizes for 3/16 inch brake lines tube.
PROFESSIONAL - MuHize focus on outstanding features and benefits of braking line. 100% brand new & made from excellent materials, and good contact.
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| Horiznext | 9.86 | ✅ | ✅ | ✅ |
Made of stainless steel 304, heavy duty, durable and corrosion resistant.
1/4" outer diameter tube
Fittings for connecting and extending stainless steel, copper, rigid and semi-rigid plastic tubing
Maximum working pressure of 600 psi
Temperature range from -100 to +660 degrees ℉
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| MuHize® Direct | 9.85 | ✅ | ✅ | ✅ |
PACKAGE INCLUDE - MuHize upgraded Brake Fittings Replacement (Pack of 15): ① 5 x 3/8-24 threads unions; ② 10 x 3/8-24 threads nuts. Note：Both the unions and nuts is 3/8-24 threads (regular 3/16 inch tube fitting size) . Please check before shopping!
INVERTED FLARE UNION- Any 2 (3/16 inch) brake lines can be easy to joined with Muhize unions. both the sizes for unions and nuts are both 3/8-24 threads, which is the regular brake fitting size for 3/16 inch tube.
HIGHER QUALITY - MuHize brake fittings are made of durable brass with unique rust corrosion proofing technology.
WIDELY APPLICATION - MuHize 3/8' - 24 threads fittings commonly fits for regular inverted flare/ double flare sizes for 3/16 inch brake lines tube.
PROFESSIONAL - MuHize focus on outstanding features and benefits of braking line. 100% brand new & made from excellent materials, and good contact.
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| Southwest Performance Parts | 9.72 | ✅ | ✅ | ✅ |
12 Piece 3/8 Inch-24 Threads Brake Line Fittings Assortment - for 3/16 Inch Tube (4 Unions, 8 Nuts)
These brake line fittings are made of durable brass to prevent rust and plated for corrosion resistance. Both the unions and nuts is metric 3/8-24 threads (regular 3/16 inch tube fitting size)
Intended for most common inverted flare/ double flare sizes for 3/16 inch tube, for use with 3/16 inch steel, poly coated or copper brake lines
Compatible with most common inverted flare/ double flare sizes for 3/16 inch tube
Package Inclusions - 12 piece brake line fittings in the package, include 4 pieces unions and 8 pieces nuts
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| derpipe | 9.86 | ✅ | ✅ | ✅ |
Size: 1/4”Barb x 1/4”Barb
Material: 304 stainless steel,heavy duty,last for long lifetime,resistant to corrosion,low magnetic permeability.
Bulkhead union coupling for connecting two hoses with the same
The joint of two openings are two thick hexagonal nuts, that form bulkhead tank function.
Barbed fitting creates a tight seal on flexible and semi-rigid hose when used with a hose clamp or crimp sleeve or ferrule (not included).
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| derpipe | 9.86 | ✅ | ✅ | ✅ |
Size: 5/16”Barb x 5/16”Barb
Material: 304 stainless steel,heavy duty,last for long lifetime,resistant to corrosion,low magnetic permeability.
Bulkhead union coupling for connecting two hoses with the same
The joint of two openings are two thick hexagonal nuts, that form bulkhead tank function.
Barbed fitting creates a tight seal on flexible and semi-rigid hose when used with a hose clamp or crimp sleeve or ferrule (not included).
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| derpipe | 9.86 | ✅ | ✅ | ✅ |
Size: 3/8”Barb x 3/8”Barb
Material: 304 stainless steel,heavy duty,last for long lifetime,resistant to corrosion,low magnetic permeability.
Bulkhead union coupling for connecting two hoses with the same
The joint of two openings are two thick hexagonal nuts, that form bulkhead tank function.
Barbed fitting creates a tight seal on flexible and semi-rigid hose when used with a hose clamp or crimp sleeve or ferrule (not included).
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| CHILLWAVES | 7.20 | ✅ | ✅ | ✅ |
SIZE - 1/2" Tube OD x 1/2" Tube OD, Compression Tube Fitting mainly consists of a fitting body with a 24 degree tapered hole, a ferrule with a sharp inner edge, and a nut for compression.
MATERIAL - Made of high-quality brass, with strong wear and corrosion resistance, high compressive strength, durability, low magnetic permeability and high temperature ductility.
Use - Suitable for oil, gas, water and other non-corrosive or corrosive pipeline systems, temperature and pressure resistance, good sealing and repeatability, no need for welding and flaring tools, easy disassembly, installation and maintenance, etc.
WORKING PRESSURE & TEMPERATURE - 1200PSI maximum working pressure, temperature range -65°F to +250°F (-53°C to +121°C)
WORKING PRINCIPLE - Compression Tube Fitting is to compress the ferrule by thread interlocking, and the two ends of the inner diameter of the ferrule tightly wrap the tube due to radial shrinkage, which plays a sealing role and realizes the sealing and tightening effect between the joint and the tube.
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| CHILLWAVES | 7.16 | ✅ | ✅ | ✅ |
SIZE - 1/4" Tube OD x 1/4" Tube OD x 1/4" Tube OD, Compression Tube Fitting mainly consists of a fitting body with a 24 degree tapered hole, a ferrule with a sharp inner edge, and a nut for compression.
MATERIAL - Made of high-quality brass, with strong wear and corrosion resistance, high compressive strength, durability, low magnetic permeability and high temperature ductility.
Use - Suitable for oil, gas, water and other non-corrosive or corrosive pipeline systems, temperature and pressure resistance, good sealing and repeatability, no need for welding and flaring tools, easy disassembly, installation and maintenance, etc.
WORKING PRESSURE & TEMPERATURE - 1200PSI maximum working pressure, temperature range -65°F to +250°F (-53°C to +121°C)
WORKING PRINCIPLE - Compression Tube Fitting is to compress the ferrule by thread interlocking, and the two ends of the inner diameter of the ferrule tightly wrap the tube due to radial shrinkage, which plays a sealing role and realizes the sealing and tightening effect between the joint and the tube.
| SELLER | SELLER SCORE | AMAZON FULFILLED | PRIME | FREE SHIPPING |
|---|---|---|---|---|
| Best Hardware Direct | 8.03 | ✅ | ✅ | ✅ |
Package Qty : 1 Piece Fitting + 2 Nuts
Material : Copper
Size : 3/8"
Application: Air Conditioning Copper Pipe
Sturdy and Durable, and are not easily damaged when installed.
Here is the list of top-rated brands that were evaluated by PM.
| Brand | Count |
|---|---|
| Derpipe | 3 |
| Chillwaves | 2 |
| Muhize | 2 |
| A-Team Performance | 1 |
| Anderson Metals | 1 |
| Frienda | 1 |
| Hongbow Hardware | 1 |
| Horiznext | 1 |
| Ltwfitting | 1 |
| Minimprover | 1 |
We've carried out a comprehensive analysis of 4,268 reviews on fitting nuts, using our selection criteria to identify the best options in the categories. Our findings reveal that most customers typically select fitting nuts priced around $32.22, with top brands including and
Our team of expert editors reviewed these high-quality items and handpicked the top 14 fitting nuts for your consideration. We've also done extensive research on numerous sellers, identifying the best ones in the categories category. These include and .
We are dedicated to assisting our users in finding the right fittings Products based on their needs, saving them considerable time when choosing which fitting nuts to buy. We take pride in the number of satisfied users we've helped through our thorough and insightful reviews.
PickSmartly is dedicated to creating a platform designed to streamline your shopping experience, empowering you to make well-informed purchasing decisions with minimal time and effort. At the heart of our mission is the commitment to earning and maintaining the trust of our users, as we believe this to be fundamental to the services we provide.
When you engage with our websites, services, or tools, we or our approved service providers may utilize cookies to store information. This is done to enhance your user experience by making it more efficient, secure, and tailored to your preferences, as well as for marketing objectives.
We are an Amazon Associate and earn commissions from qualifying purchases. Our participation in the Amazon Services LLC Associates Program, an affiliate advertising initiative, provides us with a means to generate income through links to Amazon.com and its affiliated websites. Please note that Amazon, Amazon Prime, their logos, and the Amazon Prime logo are registered trademarks of Amazon.com, Inc., or its associated companies.
