We can see that the EFG tensor in the toy model has an axial symmetry in its PAS in two ways. First, by looking at the expression for the EFG tensor we notice that V_xx = -a, V_yy = -a and V_zz = 2a (where a is the prefactor in the expression). Then according to the definition of eta, eta = (V_xx – V_yy)/V_zz it is easy to see that this is zero. This means that there is axial symmetry as was discussed in the video. The other way to see that there is axial symmetry is by looking at the schematic picture of the toy model. In the PAS the z-axis is aligned with the two electrons. Now any rotation around this z-axis will leave the system of the two electrons invariant, i.e. there is an axial symmetry.