The indoor receiver has a plug-in 12VDC power supply with a 6 foot cord. The receiver may be placed on a counter top, table or hung on the wall. The electronic LED counter feature allows you to either count customers or count unexpected visitors / vehicles moving in your driveway. There is a reset button next to the counter, when pressed it will zero out the counter. This unit also has six dip switches on the back of this unit. Numbers 1-4 must match transmitter. Number 5 controls the output of the 12VDC terminals on the back of the receiver with a one second or five second 12VDC output, Number 6 is not used. The terminal screws on the receiver back give you the option of adding a bell, buzzer, horn, siren, strobe or anything that is 12VDC operated. The other speaker terminal (SPKR) screws allow you to add an auxiliary speaker via a wire connection to get the same "Ding Dong" sound as the receiver. A volume control knob adjusts volume on receiver and auxiliary speaker and a different tone is generated depending on which transmitter (zone) is activated. For optimal reception the antenna will swivel 360 degrees.