  We present the results of the combined photometric and spectroscopic analysis
of a bright (V=9.14), nearby (d=31 pc), late-type detached eclipsing binary AK
Fornacis. This P=3.981 d system has not been previously recognised as a
double-lined spectroscopic binary, and this is the first full physical model of
this unique target. With the FEROS, CORALIE and HARPS spectrographs we
collected a number of high-resolution spectra in order to calculate radial
velocities of both components of the binary. Measurements were done with our
own disentangling procedure and the TODCOR technique, and were later combined
with the photometry from the ASAS and SuperWASP archives. We also performed an
atmospheric analysis of the component spectra with the Spectroscopy Made Easy
(SME) package. Our analysis shows that AK For consists of two active, cool
dwarfs having masses of $M_1=0.6958 \pm 0.0010$ and $M_2=0.6355 \pm 0.0007$
M$_\odot$ and radii of $R_1=0.687 \pm 0.020$ and $R_2=0.609 \pm 0.016$
R$_\odot$, slightly less metal abundant than the Sun. Parameters of both
components are well reproduced by the models.
  AK For is the brightest system among the known eclipsing binaries with K or M
type stars. Its orbital period is one of the longest and rotational velocities
one of the lowest, which allows us to obtain very precise radial velocity
measurements. The precision in physical parameters we obtained places AK For
among the binaries with the best mass measurements in the literature. It also
fills the gap in our knowledge of stars in the range of 0.5-0.8 M$_\odot$, and
between short and long-period systems. All this makes AK For a unique benchmark
for understanding the properties of low-mass stars.
