With this brass adapter, which we made especially for our metal gearbox 1:125 (art. no. 63125), the gearbox axle can be connected to a threaded rod M 1.2. For this purpose, one side of the adapter has a 1.2 mm hole (for the gear axle) and on the other side an M 1.2 thread has been cut (for the threaded rod).
The outer diameter is 2 mm, the length of the adapter 7 mm.