Allowing precise cutting and stripping, the new assembly tool from HARTING significantly simplifies and speeds up the assembly of polymer optical fibers while also achieving low attenuation levels. Both single optical fiber conductors are simultaneously stripped and cut with a circular knife in the duplex procedure. The front face of the optical fiber is cut to such high precision in this procedure that there is no need for subsequent polishing. In order to guarantee that each cut is precise, the circular knife is pre-clocked with each processing step. A mechanical counter permanently integrated in the gripper registers the number of steps carried out. One cutting unit can be used for more than 1,200 cuts. At the end of its service life, the cutting tool blocks. The user can replace it with a new cutting unit in a simple step. A visual display signals how many cuts can still be made, allowing arrangements for a new cutting unit to be made in good time. The tool consequently guarantees reliable assembly with reproducible cutting and attenuation results.