  Recently completely new types of domain walls (DWs) have been discovered in
helical magnets, consisting generically of a regular array of {\it pairs} of
magnetic vortex lines \cite{Li+12}. Only for special orientations DWs are free
of vortices. In this article we calculate their elastic and pinning properties,
using the pitch angle $\theta$ as a small parameter. In particular we show that
vortex free DWs exhibit long range elasticity which makes them very stiff and
suppresses their pinning by impurities. Their roughening transition temperature
is of the order of the N\'eel temperature. DWs including vortices (either by
orientation or due to step formation above their roughening transition) show
short range elasticity and strong pinning by impurities. These results apply
both to centro-symmetric as well as to non-centrosymmetric systems. The
application to chiral liquid crystals is briefly discussed.
