  The relative roles of metallicity and surface gravity on the near-infrared
spectra of late-T brown dwarfs are not yet fully understood, and evolutionary
models still need to be calibrated in order to provide accurate estimates of
brown dwarf physical parameters from measured spectra. The T-type brown dwarfs
Eps Indi Ba and Bb forming the tightly bound binary Eps Indi B, which orbits
the K4V star Eps Indi A, are nowadays the only such benchmark T dwarfs for
which all important physical parameters such as metallicity, age and mass are
(or soon will be) known. We present spatially resolved VLT/NACO images and low
resolution spectra of Eps Indi B in the J, H and K near-infrared bands. The
spectral types of Eps Indi Ba and Bb are determined by direct comparison of the
flux-calibrated JHK spectra with T dwarf standard template spectra and also by
NIR spectral indices. Eps Indi Bb is confirmed as a T6 while the spectral type
of Eps Indi Ba is T1.5 so somewhat later than the previously reported T1.
Constrained values for surface gravity and effective temperature are derived by
comparison with model spectra. The evolutionary models predict masses around
about 53 M_J for Eps Indi Ba and about 34 M_J for Eps Indi Bb, slightly higher
than previously reported values. The suppressed J-band and enhanced K-band flux
of Eps Indi Ba indicates that a noticeable cloud layer is still present in a
T1.5 dwarf while no clouds are needed to model the spectrum of Eps Indi Bb.
