... ;3, the fin-tube material: 1, base tube: carbon steel, stainless steel, copper, copper alloy, titanium and so on. 2, fin: aluminum (extruded type or ... ), copper (winding type).4, finned tube size: 1, base tube: OD16, OD19, OD1 ", OD38; 2, fin: OD34, OD44, OD57, OD70 (or by request). extruded fin tube