English to Italian Tech/Engineering Engineering (general)

Come tradurreste il passaggio "proportionally opposite that..."?

" Due to the translational mobility of the rod 20 along the axis X-X, the axial span of the deployed part 21 varies proportionally opposite that of the non-deployed part 22 based on the axial position of the rod 20 relative to the case 10. Thus, when the rod 20 is translated to the left in figure 1, the axial span of its deployed part 21 increases, while the axial span of its non-deployed part 22 decreases in a corresponding manner, until reaching a minimum span."


Grazie !