The Aprilaire 8818 Distribution Panel is a switch controlled communication bus that can be wired to 8 Aprilaire Model 8878 thermostats. This allows thermostat communication (transmit, receive, or both) to be turned on and off at one convenient location which simplifies installation and trouble-shooting. Each thermostat station on the distribution panel has an On/Off switch for power. This allows isolation of any one thermostat to simplify trouble-shooting. Order one 8818 Distribution Panel per every eight 8870 thermostats.