Just install it. it has already had the calibration that can be done.
Calibration is done on all but digital speedos by inputing a given frequency (revolutions on cable driven ones) and verifying that 60mph results (for mph speedos). The frequency or numbers of turns is written on the back of the speedo as K= or W=.
If this doesn't result in proper speed due to changes in tire size or gear changes then custom calibration is needed or a converter installed.
Bosch Master, ASE Master, L1
33 years MB technician