The magnetic door contact serves as a useful alternative to the above transmitters, especially for built up areas where RF interference may be an issue. It has transmitted range of about 180m line of site. Has a 8 pin jumper track for setting unique RF code. (Can be set for 1.5M, 2.2M, or 4.7M Oscillation Resistance). Oscillation resistance value must be matched to the particular receiver to which the sensor will be linked (i.e. 2.2M).Note: An indoor repeater may be required to repeat the RF signal for buildings with thick walls and flooring and or for PIRs spaced long distances away from the base receiver.