... : carbon steel, alloy steel, stainless steel, cast steel, copper, aluminum. From the production process points include: stamping, push system, butt, forging ... . From the specification points include: 90 degrees, 45 degrees, 180 degrees, ... , 1.5 D, 2 D, 2.5 D, 3 D. From use kinds points include: high elbow, low bend, thick wall elbow ...