A fin body to be housed inside a heat exchange tube having a planar configuration, which heat exchange tube is from among the exchange tubes extending along a longitudinal direction X-X' and comprising two planar inner faces (2.1, 2.2) parallel to and facing one another; the fin body is configured in the form of a plate and formed from a metal sheet having a thickness e, bent into a plurality of consecutive bends extending according to a direction Z, wherein the direction Z is intended for being parallel to the longitudinal direction X-X' of the heat exchange tube housing it, and wherein; the bends are configured by alternating between a first plane (P 1 ) and a second plane (P 2 ) parallel to the first plane (P 1 ), and with both planes being spaced from one another, wherein the first plane (P 1 ) and the second plane (P 2 ) are intended to coincide with the planar inner faces of the heat exchange tube parallel to and facing one another; the bends, according to a transverse section (P T ) with respect to direction z, show a periodic zigzag wavy path (T), wherein - said wavy path (T) comprises segments (1.1), the segments (1.1) being connected by vertices (1.2) located in the peaks of maximum amplitude; - the characteristic width (s) is half the wavelength of the wavy path (T) and the characteristic height (h) is the distance between peaks of maximum amplitude of the wavy path (T), wherein the wavy path (T) according to the transverse section (P T ) has a channel width ( s ch ) to plate height ( h out ) ratio in the interval of [0.15-0.5], wherein s ch = s ― e and h out = h + e, wherein the zigzag transverse section (P T ) extends according to direction Z following a longitudinal wavy path, and wherein said longitudinal wavy path has a minimum characteristic radius (r) to pitch (p), r/p, ratio in the range of [0.2, 2]. the fin body is configured in the form of a plate and formed from a metal sheet having a thickness e, bent into a plurality of consecutive bends extending according to a direction Z, wherein the direction Z is intended for being parallel to the longitudinal direction X-X' of the heat exchange tube housing it, and wherein; the bends are configured by alternating between a first plane (P 1 ) and a second plane (P 2 ) parallel to the first plane (P 1 ), and with both planes being spaced from one another, wherein the first plane (P 1 ) and the second plane (P 2 ) are intended to coincide with the planar inner faces of the heat exchange tube parallel to and facing one another; the bends, according to a transverse section (P T ) with respect to direction z, show a periodic zigzag wavy path (T), wherein - said wavy path (T) comprises segments (1.1), the segments (1.1) being connected by vertices (1.2) located in the peaks of maximum amplitude; - the characteristic width (s) is half the wavelength of the wavy path (T) and the characteristic height (h) is the distance between peaks of maximum amplitude of the wavy path (T), - said wavy path (T) comprises segments (1.1), the segments (1.1) being connected by vertices (1.2) located in the peaks of maximum amplitude; - the characteristic width (s) is half the wavelength of the wavy path (T) and the characteristic height (h) is the distance between peaks of maximum amplitude of the wavy path (T), wherein the wavy path (T) according to the transverse section (P T ) has a channel width ( s ch ) to plate height ( h out ) ratio in the interval of [0.15-0.5], wherein s ch = s ― e and h out = h + e, wherein the zigzag transverse section (P T ) extends according to direction Z following a longitudinal wavy path, and wherein said longitudinal wavy path has a minimum characteristic radius (r) to pitch (p), r/p, ratio in the range of [0.2, 2]. <EOS>