ICM modules consist of 4, 8 or 22 stations each; allowing you to build a controller more closely matching the total number of stations desired.
The ICC and I2C controllers are supplied with one factory-installed station module for up to 8 stations. Additional modules are purchased separately. Additional modules may be added in increments of 4 or 8 stations for the original ICC controller to a maximum of 32 stations with a plastic cabinet and a maximum of 48 stations with a metal or stainless steel cabinet. A 22 station add-on module can be used to expand the I2C controller's station capability to a maximum of 38 stations with plastic cabinet and maximum of 54 stations with metal or stainless steel cabinet.