22-Piece Fitting Set (Upgraded) ① 2 x 3/16" (3/8-24) Thread Unions ② 2 x 3/16" (9/16-18) Inverted Tube Nuts ③ 2 x 3/16" (1/2-20) Inverted Tube Nuts ④ 2 x 3/16" (7/16-24) Inverted Tube Nuts ⑤ 14 x 3/16" (3/8-24) Inverted Tube Nuts Premium-Grade Materials Copper-coated brake line: Crafted from alloy steel to resist oxidation and corrosion. All brake pipe fittings: Made of anti-rust brass for extended service life and reliable performance. Single Flare Functionality .