All tubes are CNC mandrel bent for optimal flow for all 180 degree bends or also called U bends with 6" legs. Made from 304 stainless steel for maximum corrosion resistance. The diameter of tubes is 3-1/2" with a .065 wall thickness. Smooth, wrinkle free bends are great for custom fabrication. These bends come with a lifetime warranty and proudly made in the USA.