too sparse, for us to comment on the commonality of such geometries, the observations presented in this paper can enable testing of theoretical mechanisms involving magnetic fields for shaping PPNe.

As aforementioned, a complete MHD model (i.e. taking into account the detailed hydrodynamics information of the source) would therefore greatly help in determining the field strength needed to trigger the magnetic structures that are observed and if/how it would affect the dynamics of the outflows.\

Summary and Conclusions {#final}
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We present a polarization analysis of OH 231.8+4.2 with ALMA at the high spatial resolution of 0.5”. The new data allowed us to have a clear picture of the magnetic field geometry at smaller scales. In combination with other interferometric polarization data, we now have new insights into the whole magnetic field structure which might govern or be closely related to the object geometry. The main findings are described below.\
$\bullet$ ALMA revealed well organized $\overrightarrow{E}$-vectors in the bright A and B regions corresponding to the northern outflow and the waist of OH 231.8+4.2. The $\overrightarrow{B}$-vectors are consistent with an hourglass morphology whose origin is coincident with the location of the central star of the nebula. In the southern outflow, 