Designed by a team of electrical engineers, the Ultrasonic Motion Detector uses ultrasonic sound waves to detect motion. This uses sound waves at a frequency higher than humans are able to hear – typically in the range 30kHz to 10MHz. Transducers comprise a pair of devices, one is a transmitter and one is a receiver. A sound pulse is sent out at a given frequency and it is reflected and captured by the receiver.
 
To use, just point it at the area you wish to detect motion in. The LED display will show how far away the object is in feet. The green light means the object is moving away from the motion detector. The red light means the object is moving closer to the motion detector.
 
Features
ATMega328 Microcontroller
Motion sensing
Tripod Mounting
Uses a 9V battery
 
https://youtu.be/Z-9i7t7XVxw
6 week Lead Time.