  This article presents the MEG II Cylindrical Drift CHamber (CDCH), a key
detector for the phase 2 of MEG, which aims at reaching a sensitivity level of
the order of $6 \times 10^{-14}$ for the charged Lepton Flavour Violating
$\mu^+ \rightarrow \mbox{e}^+ \gamma$ decay. CDCH is designed to overcome the
limitations of the MEG $\mbox{e}^+$ tracker and guarantee the proper operation
at high rates with long-term detector stability. CDCH is a low-mass unique
volume detector with high granularity: 9 layers of 192 drift cells, few mm
wide, defined by $\approx 12000$ wires in a stereo configuration for
longitudinal hit localization. The total radiation length is $1.5 \times
10^{-3}$ $\mbox{X}_0$, thus minimizing the Multiple Coulomb Scattering (MCS)
contribution and allowing for a single-hit resolution of 110 $\mu$m and a
momentum resolution of 130 keV/c. CDCH integration into the MEG II experimental
apparatus will start in this year.
