Inner radius, polarization and circular truncation of the set

The difference of the reduced module $m(B,0)$ of an open set $B$, $0\in B$, and the reduced module $m(B_r,0)$ of its circular truncation $B_r$, where $B_r=B\cap\{|z|<r\}$, is considered. It is proved that in the case of polarization and circular symmetrization this difference does not decrease.