The receiver has both normally open and normally closed terminals for each channel. The state of these terminals changes when it receives a signal from a transmitter, eg. the N/C contact becomes open and the N/O contact closes. When the signal stops, the contacts revert to the original state. A transistor output of 12V 25mA that can be connected to a supplied buzzer or other device becomes live when the battery low signal is received from a transmitter. A 12VDC power supply is required. Contacts are rated at 1A 24VAC/DC. Also available in 4-Channel and 1-Channel versions. One channel version does not have the battery low output.