Aprilaire system control for communicating thermostat system. Used in conjunction with the 8870 communicating thermostats and 8818 distribution panel. Includes preloaded software. This device enables the Aprilaire home & business automation system to be operated with the use of an on-site computer. Requires local PC for program changes. Has LAN socket for connection to existing LAN. Will serve up to 32 thermostats and 256 control relays. Preprogramed with Windows compatable software. When interfaced with proper Aprilaire components this device will permit you to program and monitor your facility via the internet.