1.carbon steel 2.single wall 3.30degree elbow , 4.black , 5.diameter is 5",6",7",8",10",12" Specification:Material: Carbon steelthickness:1mm or 3mmDiameter: From 15 CM to 200 CMDegree: 15 degree to 75 degreesingle wallHeat resistance: 500 ' CWe can do OEM service, if you are interested, please feel free to send us inquiry.