  Extreme high synchrotron peaked blazars (EHBLs) are amongst the most powerful
accelerators found in nature. Usually the synchrotron peak frequency of an EHBL
is above $10^{17}\,$Hz, i.e., lies in the range of medium to hard X-rays making
them ideal sources to study particle acceleration and radiative processes. EHBL
objects are commonly observed at energies beyond several TeV, making them also
powerful probes of gamma-ray absorption in the intergalactic medium. During the
last decade, several attempts have been made to increase the number of EHBL
detected at TeV energies and probe their spectral characteristics. Here we
report new detections of EHBLs in the TeV energy regime, each at a redshift of
less than 0.2, by the High Energy Stereoscopic System (H.E.S.S.). Also, we
report on X-ray observations of these EHBLs candidates with Swift XRT. In
conjunction with the very high energy observations, this allows us to probe the
radiation mechanisms and the underlying particle acceleration processes.
