  The nuclear stellar disc (NSD) is a dense stellar structure at the centre of
our Galaxy. Given its proximity, it constitutes a unique laboratory to
understand other galactic nuclei. Nevertheless, the high crowding and
extinction hamper its study, and even its morphology and kinematics are not yet
totally clear. In this work we use NSD red clump stars, whose intrinsic
properties are well known, to trace the kinematics of the NSD and to compute
the distance and extinction towards the edges of the NSD. We used publicly
available proper motion and photometric catalogues of the NSD to distinguish
red clump stars by using a colour-magnitude diagram. We then applied a Gaussian
mixture model to obtain the proper motion distribution, and computed the
extinction and distance towards stars with different kinematics. We obtained
that the proper motion distributions contain NSD stars rotating eastwards and
westwards, plus some contamination from Galactic bulge/bar stars, in agreement
with previous work. We computed the distance and extinction towards the
eastward- and westward-moving stars and concluded that the latter are $\sim300$
pc beyond, indicating a similar structure along and across the line of sight,
and consistent with an axisymmetric structure of the NSD. Moreover, we found
that the extinction within the NSD is relatively low and accounts for less than
10 % of the total extinction of the stars belonging to the farthest edge of the
NSD.
