  The realism of current models of the penumbra is assessed by comparing their
predictions with the plasma properties of penumbral filaments as retrieved from
spectropolarimetric observations. The spectropolarimeter onboard Hinode allows
us to distinguish for the first time the fine structure of the penumbra.
Therefore, we can use one-component inversions to obtain the stratifications of
plasma parameters in each pixel. The correlations between the plasma parameters
and the continuum intensity are studied. We find that, in the outer penumbra,
the stronger flows and higher values of magnetic field inclination tend to be
located in dark filaments. This finding does not seem to be compatible with the
scenario of a field-free gappy penumbra.
