The ELK-M1XRF2G is a Wireless (RF) Receiver and Input Expander for use with theELK-M1 and ELK-M1EZ8 Controls. The receiver connects to the four (4) wire data (keypad) bus of the control and integrates in much the same way as a M1XIN hardware zone expander except that a single M1XRF can handle up to 144 wireless zones(e.g. transmitter sensors or points).