Short answer: copper-nickel (Cunifer/NiCopp) bends by hand and resists corrosion as well as stainless without work-hardening, which is why most brake line replacement today is copper-nickel rather than steel or stainless tube. Stainless still has a place, it’s harder, more abrasion-resistant, and looks the part on a show car, but it comes with real tradeoffs the copper-nickel doesn’t.
Copper-nickel: the practical default
Copper-nickel alloy (branded as Cunifer, NiCopp, or Ezi-Bend depending on the supplier) bends easily by hand or with a simple hand bender, without the springback or kinking that plain steel tube is prone to. It doesn’t rust, ever, and it doesn’t work-harden the way stainless does as you bend it, meaning you can reshape a run without the material fighting you more with every bend. The tradeoff is that it’s softer, so it’s more vulnerable to abrasion or a rock strike where a line runs exposed and unprotected.
Stainless steel: harder, less forgiving
Stainless brake line resists corrosion just as well as copper-nickel and is significantly more resistant to abrasion and impact, which matters on off-road builds or anywhere a line runs somewhere it might get struck. The cost is workability, stainless work-hardens as it’s bent, so tight bends get progressively harder to form and are more prone to cracking if pushed too far, and it demands more from both the bender and the flaring tool used on it.
Steel (uncoated or zinc/terne-coated): the OEM baseline, and why it’s usually replaced
Most factory brake lines are coated steel, not because it’s the best material but because it’s the cheapest to run at scale. It’s the one that rusts from the inside out on lines with any age on them, which is the actual reason most brake line replacement jobs happen in the first place, coated steel looks fine on the outside long after it’s thinned dangerously on the inside.
What we stock
BrakeQuip Products carries copper-nickel brake line in multiple sizes, BQBRAKETUBE, and stainless steel tube for builds where abrasion resistance matters more than ease of bending, including T187-20SS. Whichever material you choose, see our flaring guide before cutting into it, stainless in particular punishes a rushed flare.