Proflow Exhaust Tubing, Mandrel U-Bend, 180 Degree, Steel, 18-Gauge 2-1/2in, 3.50 in. Bend - PFEEU212Part Number: PFEEU212 Fabricate your race exhaust with U and J mandrel bends from Proflow. Crafted from 16 gauge and 18 gauge steel, these exhaust tubing U bends and J bends are mandrel bent to keep exhaust flow high and your performance maximized. Most U bends have either 9 or 7. 5 legs, while their J bends have both 3 and 15 legs. Are you creating a special fit exhaust for your race car? Use Proflow U and J mandrel bends in your build.