There are several differences. The internal structure and the housing of the the Pinion Smart.Shift gearbox were modified to cope with stronger shifting forces. In addition, a cadence sensor was integrated into the gearbox. Pinion Smart.Shift gearboxes are marked with an "i" in the name. This is visible on the protective film and on the series label. A Smart.Shift box is not compatible with "conventional" Pinion P and C line gearboxes. Conversion is prohibited.