Luminite 4 zone xpander module relay expansion module for rx16 this module plugs on to the rx16 mother board to give an extra 4 outputs the rx16 comes with one module as standard which acts on codes 1 to 4 if a pc4 is plugged on to the second position it will act on codes 5 to 8 the third position is 9 to 12 and the fourth is 13 to 16