Abstract: The present invention relates to a fin body intended for being housed inside a heat exchange tube which is one from among heat exchange tubes showing a planar configuration. The fin body is configured in the form of a plate, this plate being the one inserted into the heat exchange tube. The plate is configured from a metal sheet bent into a plurality of consecutive bends. The invention is characterized by a range of characteristic width to height ratio in the interval of 0.15-0.5, and according to more specific cases, in the lower subranges. As a result, the fin gives rise to a heat exchange tube with a higher efficiency than fins known in the state of the art without penalizing the pressure drop.