Dartin for Divorce

The different nut and thread sizes with same ID as brake lines are to keep idiot proof when connecting lines to proportioning valve so you don't connect line that's supposed to go to rear to say left front.
On the ni-copper lines, they are better than OEM steel and easier to work with all around including the dreaded double flair. I learned a tip that really helps when double flaring, small round file and clean up the inside of cut line so shards of cut line don't botch up flairs.