The Dakota Alert DCMT-4000 Motion Transmitter is a passive infrared (IR) wireless motion detector helps protect your home and property from intruders and theft. Whenever the unit detects a person or vehicle in the monitored area, it sends a signal to the DCR-4000 receiver (sold separately), that automatically triggers an alarm. Detection Range Up to 50-Feet. The transmitter can detect motion at a distance of up to 50-Feet and sends a signal back to the receiver located within 1 mile (may vary depending on the environment). Expand Your System. You can connect multiple motion detectors (or other transmitters) to the DCR-4000 receiver unit to create a complete security system. Different Tunes to Distinguish Zones. The transmitter unit can be programmed up to 12 different tunes to distinguish between different zones from where the signal has been detected. A built-in volume control allows you to set the sound to the desired level.