Scans and controls four devices! Control 4 devices in your environment by activating a capability switch. Just hold your switch and 4 lights flash sequentially for each of your devices. Releasing the switch at a chosen location changes the state of that appliance. Example: if a lamp was on and you selected the indicator light by releasing your switch, it would turn off the lamp. The control unit is supplied with two appliance modules (Receivers with a wall outlet). If you want to control 4 separate A.C. electronic devices, you need to purchase 2 additional receivers.