Summary

Effective method to keep the grass small. No nylon wire - I take a steel wire with 1mm diameter.

Additional parts!
You need two nuts (3mm metric) and two 3mm screws to fix the wire at the right position. Only one of the screw fix the wire. The other one must be at this position for the symmetric design (fast rotation).

The second part can be used for Einhell model RT350. The same function but a little smaller dimensions.