Instruments for size inspection of the types VP and VM can be upgraded to accommodate longitudinal dynamic measurements. A longitudinal dynamic adapter and the respective electronic measuring unit are added and work together with the gear and spline software LDYN. With this configuration it is possible to dynamically detect and repeat the dimension over/between balls across the full length of the gearing during inspection. In addition, the longitudinal dynamic evaluation also reveals form errors such as crowning, conicality and roundness of the workpiece. Simple statistical values such as Cp and Cpk can also be calculated with the software.