What is the difference between the products FXM / FXR 410 and FXM / FXR 160 (contra angle)?

The main difference is related to the reduction system. The models FXM 410 4:1 and FXR 410 4:1, the speed reduction is 4:1, ie; for every four rotation of the micromotor, the file of the contra angle will run 1 rotation (or oscillation in the case of line FXR). For the models FXM 160 16:1 and FXR 160 16:1, the speed reduction is 16:1, ie; each16 rotations of the micromotor, the file of the contra angle will have performed one rotation (or oscillation in the case of line FXR).