  The emission of the so-called extreme BL Lacs poses challenges to the
particle acceleration models. The hardness of their spectrum, $\lesssim 2$, in
the high-energy band demands unusual parameters using the standard one-zone
synchrotron self-Compton (SSC) model with a deficient magnetized plasma. Some
authors use either two-zone or hadronic/lepto-hadronic models to relax these
atypical values. In this work, we present a lepto-hadronic two-zone model to
explain the multi-wavelength observations of the six best-known
\textit{extreme} BL Lacs. The very-high-energy gamma-ray observations are
described by the photo-hadronic processes in a blob close to the AGN core and
by SSC and external inverse Compton-processes in an outer blob. The
photo-hadronic interactions occur when accelerated protons in the inner blob
interact with annihilation line photons from a sub-relativistic pair plasma.
The X-ray observations are described by synchrotron radiation from the outer
blob. The parameter values found from the description of the spectral energy
distribution for each object with our phenomenological model are similar to
each other, and lie in the typical range reported in BL Lacs.
