Using the rotary switch you can determine a step to which the sequencer instantly will "jump" as soon a gate signal is present at the according input of the expander. Alternatively you can command this manually by using the button.
All the rotary switches have not only one but four OFF positions so you can quickly deactivate the set function, for instance when playing live.
per 569's row: one gate input
5U module in Moog form factor, one unit wide