Easily monitor vehicle traffic and pedestrians with this driveway motion sensor alarm. The TWO motion detectors are perfect for industrial sector or residential properties that require snow plowing, have heavy truck traffic, must monitor forklift traffic, or can't use driveway signal hoses in their driveway alert systems. The wireless driveway alarms do not use an air hose â?? instead, they detects movement up to 50' in front of it and rings the TWO receiver chimes each time movement is detected from up to 1/2 a mile away. The driveway sensors have a sensitivity adjustment knob that allows you to increase or decrease the depth of monitoring in front of the Milton driveway sensor. The sensors uses a 9 volt transistor battery. The chimes plug into an ordinary electrical outlet, produce a soft ring and have a built-in audio volume control. The driveway chime alarms will play one of twelve different tunes that are selected in the sensor. The TWO Milto"Original" Bellâ??s are wired to the chimes using 5â?? of low-voltage electrical wiring included with this kit. The chimes have volume control and can be turned up loud enough to be heard through the door of many houses. The driveway motion detector chime kit includes all of the pieces necessary to set up your wireless driveway alarm and chime