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4LifetimeLines stainless steel brake line union, 3/16" M10x1.0 inverted flare (LTBU9SS)
4LifetimeLines stainless steel brake line union, 3/16" M10x1.0 inverted flare, view 2
4LifetimeLines stainless steel brake line union, 3/16" M10x1.0 inverted flare, view 3
4LifetimeLines stainless steel brake line union, 3/16" M10x1.0 inverted flare, view 4
4LifetimeLines stainless steel brake line union, 3/16" M10x1.0 inverted flare, view 5
4LifetimeLines stainless steel brake line union, 3/16" 3/8-24 inverted flare (LTBU3SS)
4LifetimeLines stainless steel brake line union, 3/16" 3/8-24 inverted flare, 2 pack (LTBU3SS-2)
4LifetimeLines stainless steel brake line union, 3/16" 3/8-24 bubble flare (LTBU7SS)
4LifetimeLines stainless steel brake line union, 3/16" M10x1.0 bubble flare (LTBU8SS)
4LifetimeLines stainless steel brake line union, 1/4" 7/16-24 inverted flare (LTBU4SS)
4LifetimeLines stainless steel brake line union, 1/4" 7/16-24 inverted flare, 2 pack (LTBU4SS-2)
4LifetimeLines stainless steel brake line union, 5/16" 1/2-20 inverted flare (LTBU5SS)
4LifetimeLines stainless steel brake line union, 3/8" 5/8-18 inverted flare (LTBU6SS)
4LifetimeLines stainless steel brake line union, 6 mm M12x1.0 bubble flare (LTBU10SS)
4LifetimeLines stainless steel brake line union, 3/16" M10x1.0 inverted flare (LTBU9SS)
4LifetimeLines stainless steel brake line union, 3/16" M10x1.0 inverted flare, view 2
4LifetimeLines stainless steel brake line union, 3/16" M10x1.0 inverted flare, view 3
4LifetimeLines stainless steel brake line union, 3/16" M10x1.0 inverted flare, view 4
4LifetimeLines stainless steel brake line union, 3/16" M10x1.0 inverted flare, view 5
4LifetimeLines stainless steel brake line union, 3/16" 3/8-24 inverted flare (LTBU3SS)
4LifetimeLines stainless steel brake line union, 3/16" 3/8-24 inverted flare, 2 pack (LTBU3SS-2)
4LifetimeLines stainless steel brake line union, 3/16" 3/8-24 bubble flare (LTBU7SS)
4LifetimeLines stainless steel brake line union, 3/16" M10x1.0 bubble flare (LTBU8SS)
4LifetimeLines stainless steel brake line union, 1/4" 7/16-24 inverted flare (LTBU4SS)
4LifetimeLines stainless steel brake line union, 1/4" 7/16-24 inverted flare, 2 pack (LTBU4SS-2)
4LifetimeLines stainless steel brake line union, 5/16" 1/2-20 inverted flare (LTBU5SS)
4LifetimeLines stainless steel brake line union, 3/8" 5/8-18 inverted flare (LTBU6SS)
4LifetimeLines stainless steel brake line union, 6 mm M12x1.0 bubble flare (LTBU10SS)

4LifetimeLines Stainless Steel Brake Line Unions, 3/16" to 3/8" & 6 mm, SAE & Metric

$16.00
4.7
Rated 4.7 out of 5 stars
7 Reviews

SKU: LTBU3SS

Size and thread
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Not sure what size you need? 3/16" is the most common brake line size — check the size chart or call 1 (855) 928-4024.

4LifetimeLines Stainless Steel Brake Line Unions join two lengths of brake line. Choose the line size, thread and flare type: 3/16", 1/4", 5/16", 3/8" or 6 mm line, SAE or metric threads, inverted (SAE double) or bubble (ISO) flare. Most sizes come in packs of 10; 3/16" 3/8-24 and 1/4" 7/16-24 inverted also come in packs of 2.

What's in the box

  • Stainless steel brake line unions in the size and pack you choose (10 or 2)

Sizes

Line size Thread Flare Pack SKU
3/16" 3/8-24 inverted 10 LTBU3SS
3/16" 3/8-24 inverted 2 LTBU3SS-2
3/16" 3/8-24 bubble 10 LTBU7SS
3/16" M10x1.0 inverted 10 LTBU9SS
3/16" M10x1.0 bubble 10 LTBU8SS
1/4" 7/16-24 inverted 10 LTBU4SS
1/4" 7/16-24 inverted 2 LTBU4SS-2
5/16" 1/2-20 inverted 10 LTBU5SS
3/8" 5/8-18 inverted 10 LTBU6SS
6 mm M12x1.0 bubble 10 LTBU10SS

How to use it

A union joins two lengths of brake line. Flare both line ends with the tube nuts on the line, thread one tube nut into each end of the union and tighten. Bleed the brakes and check the joint for leaks.

Brake safety note: Use only SAE double (inverted) or ISO bubble flares on hydraulic brake lines. Single flares are not safe for brake systems.

Questions

Which union do I need? Match the line size, the thread on your tube nuts and the flare type on the line ends.

Inverted or bubble? Inverted-flare unions take SAE double (inverted) flares; bubble unions take ISO bubble flares. Don't mix them.

Is there a brass or steel version? Yes. 4LifetimeLines sells brass and steel brake line unions separately.

Warranty and support

Covered by the 4Lifetime Limited Lifetime Warranty (see 4lifetimelines.com/pages/warranty). Questions? Email hello@4lifetimelines.com or call 1 (855) 928-4024, Monday–Friday, 9:00 AM–5:00 PM ET.

Type: Brake line union (joins two lines)
Material: Stainless steel
Line sizes: 3/16", 1/4", 5/16", 3/8", 6 mm
Threads: 3/8-24, 7/16-24, 1/2-20, 5/8-18, M10x1.0, M12x1.0
Flare types: Inverted (SAE double) or bubble (ISO), by option
Pack: 10, or 2 (3/16" 3/8-24 and 1/4" 7/16-24 inverted)
Vehicle fit: Universal (not vehicle-specific)
Warranty: 4Lifetime Limited Lifetime Warranty

Options and SKUs
3/16", 3/8-24 inverted, 10 pack: LTBU3SS
3/16", 3/8-24 inverted, 2 pack: LTBU3SS-2
3/16", 3/8-24 bubble, 10 pack: LTBU7SS
3/16", M10x1.0 inverted, 10 pack: LTBU9SS
3/16", M10x1.0 bubble, 10 pack: LTBU8SS
1/4", 7/16-24 inverted, 10 pack: LTBU4SS
1/4", 7/16-24 inverted, 2 pack: LTBU4SS-2
5/16", 1/2-20 inverted, 10 pack: LTBU5SS
3/8", 5/8-18 inverted, 10 pack: LTBU6SS
6 mm, M12x1.0 bubble, 10 pack: LTBU10SS

  • 4.8★ from nearly 4,000 Amazon ratings
  • Free US shipping on orders $50+
  • Ships same day when ordered by 2 PM ET (Mon–Fri)
  • Lifetime warranty on every product

Lifetime Quality, Covered — for Life

Zero Risk, Maximum Confidence

Built to Endure. Guaranteed to Perform.

One-Time Purchase. Lifetime Assurance.

Lifetime Quality, Covered — for Life

Zero Risk, Maximum Confidence

Built to Endure. Guaranteed to Perform.

One-Time Purchase. Lifetime Assurance.

Lifetime Quality, Covered — for Life

Zero Risk, Maximum Confidence

Built to Endure. Guaranteed to Perform.

One-Time Purchase. Lifetime Assurance.

Lifetime Quality, Covered — for Life

Zero Risk, Maximum Confidence

Built to Endure. Guaranteed to Perform.

One-Time Purchase. Lifetime Assurance.

Lifetime Quality, Covered — for Life

Zero Risk, Maximum Confidence

Built to Endure. Guaranteed to Perform.

One-Time Purchase. Lifetime Assurance.

Lifetime Quality, Covered — for Life

Zero Risk, Maximum Confidence

Built to Endure. Guaranteed to Perform.

One-Time Purchase. Lifetime Assurance.

Lifetime Quality, Covered — for Life

Zero Risk, Maximum Confidence

Built to Endure. Guaranteed to Perform.

One-Time Purchase. Lifetime Assurance.

4.7
Rated 4.7 out of 5 stars
Based on 7 reviews
100%would recommend this product
7 reviews
  • Rated 5 out of 5 stars
    1 year ago
    Nice stuff

    Works well and fast delivery

    CS
    charles s.
  • Rated 5 out of 5 stars
    2 years ago
    great product

    great product

    JC
    Jason C.
  • Rated 4 out of 5 stars
    2 years ago
    Stainless steel brake line union fitting metric

    I noticed on a couple of the insides of the union fittings. The machining wasn’t quite smooth. Hopefully they will seal.

    SS
    Steven S.
  • Rated 4 out of 5 stars
    2 years ago
    Finish is not great. Could

    Finish is not great. Could use a quick cleaning

    MJ
    Michael J.
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Ideal Products

Ideal stuff for fabricating brake lines brake lines at a very good price.Kit very well covers the materials for doing the whole brake line system.

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Great products, competitive prices, and fast shipping.

This was my first purchase and the experience has been fantastic. Great products, competitive prices, and fast shipping. Communication is also top notch.