  The peak of the de-absorbed energy distribution of the TeV emitting BLs can
reach values up to ~10 TeV. In the context of SSC models of relativistic
uniformly moving blobs of plasma, such high energy peak emission can be
reproduced only by assuming Doppler factors delta ~ 50. However, such high
values strongly disagree with the unification of FR I radio galaxies and BLs.
Additionally, the recent detections of slow, possibly sub-luminal velocities in
the sub-pc scale jets of the TeV BLS MKN 421 and MKN 501 suggest that the jets
in these sources decelerate very early to mildly relativistic velocities (Gamma
\~ a few). Here, we examine the possibility that the relativistic flow in the
TeV BLs decelerates lognitudinally. In this case, modest Lorentz factors
(Gamma~15), decelerating down to values compatible with the recent
interferometric observations, can reproduce the ~ few TeV peak energy of these
sources. Furthermore, such decelerating flows naturally reproduce the observed
broadband BL-FR I luminosity ratios.
