The twist shifter works with two shift cables. When the twist shifter is rotated forward (direction gear #14), than the rear shift cable 14 is pulled.
When the twist shifter is rotated backward (direction gear #1), than the front shift cable 1 is pulled. The indexing of the shifting lies not in the twist shifter as with common designs, but inside the hub. There is no wear on the indexing system nor need to adjust it.