All RC4 dimmers have a Set button for each individual dimmer output.  On a 2-channel device, these are SetA and SetB.  A 4-channel device adds SetC and SetD.

The most common use of the Set button is to assign a DMX channel and dimmer curve to the associated Dim dimmer using RC4 OneTouch; SetA is for the DimA output, SetB for DimB, and so on.