for connecting 2 (3/16 inch) brake lines together 3/16''(0.48 cm) tube size, suitable for 3/16''(0.48 cm) steel, polyethylene coated or copper brake lines. The packaging includes: 10 x Unions 20 x nuts Thread size: 0.95 cm (for 0.48 cm tube) Thread size: 3/8-24 (for 3/16'' tube).