The diagram below shows that the required overall efficiency is secured under consideration of ambient temperature and a needed minimum output torque.The measurement of overall efficiency of planetary gearbox and worm gear including the stepper motor on the field is not possible with the needed accuracy and contradicts international practice. The motor is a “black box” and the technical data are not based on a real measurement. With typical data e.g. from a catalogue or the measurement of a sample stepper motor in a laboratory environment is not sufficient. Therefore, the determination of overall efficiency in the field will have always some deviations. We consider the subject closed.