Proflow Exhaust Tubing, Mandrel -Bend, 180 Degree, Steel, 18-Gauge 3.0in. 3.50 in. Bend - PFEEJ300Part Number: PFEEJ300 Fabricate your race exhaust with U and J mandrel bends from Proflow. Crafted from 16 gauge or 18 gauge steel, these exhaust tubing U bends and J bends are mandrel bent to keep exhaust flow high and your performance maximized. Most Proflow U bends have either 9 or 7. 5 legs, while their J bends have both 3 and 15 legs. If you creating a special fit exhaust for your race ca then you need these.