  High resolution spectropolarimetric data obtained by HINODE is used to
characterize the small-scale penumbral magnetic field as well as the vertical
and horizontal component of the Evershed effect (EE).
  The results demonstrate that the penumbral velocity field differs
significantly from that of the quiet Sun. Morphological studies yield elongated
upflow channels in the inner penumbra and round downflows in the outer
penumbra. These flows are identified as the sources and the sinks of the EE.
Remarkable is the high plasma velocity in these sinks, which is much larger
when compared to the quiet Sun. Furthermore, an extraordinary high zenith angle
was found for the penumbral downflows. The small-scale velocity field within
penumbral filaments is investigated both by statistics and case studies. The
outcome of these surveys confirms the predictions of penumbral flux-tube
models. Additionally, bright penumbral downflows as well as two families of
penumbral filaments are studied. Observations of sunspots close to the solar
limb are used to review the horizontal component of the EE.
  Asymmetries of Stokes profiles prove that the penumbral plasma flow is
concentrated in the deep photosphere and that its amplitude diminishes much
faster with height when compared to the quiet Sun. Furthermore, the magnetized
character of the horizontal and the vertical EE is unequivocally confirmed. In
contrast to previous studies, this analysis proves that the sinks of the EE are
filled with a magnetic field of opposite polarity. Finally, the influence of
atmospheric parameters on the asymmetries of Stokes profiles is explored within
the framework of a two-layer model atmosphere and by means of spectral
inversion. Interestingly, it is only the polarity of the gradients with height
of the magnetic field strength that causes the sign of the total net circular
polarization in the center side penumbra.
