It looks like a PC case with a car battery attached to it.
Radar Speed Detection Device in ChinaA speed detector, sometimes called a fuzz buster, is a passive electronic device used by motorists to determine if their speed is being monitored by law enforcement agencies via a radar unit, thereby potentially avoiding prosecution for speeding. Only doppler radar-based devices can be detected — other speed measuring devices including those using ANPR, piezo sensors and VASCAR technology cannot be detected, while LIDAR devices require a different type of sensor. Most of today's speed detectors detect signals across a variety of wavelength bands
One of the technologies that law enforcement agencies can use to measure the speed of a moving vehicle uses doppler radar to beam a radio wave at the vehicle, and then infer the vehicle's speed by measuring the Doppler effect-moderated change in the reflected wave's frequency. Radar guns can be hand-held, vehicle mounted or strategically mounted.
Radar detectors use a superheterodyne receiver to detect these electromagnetic emissions from the radar gun, and raise an alarm to notify the motorist when a transmission is detected. False alarms can occur however due to the large number of devices, such as automatic door openers, that operate in the same part of the electromagnetic spectrum as radar guns.
In recent years some radar detectors have added GPS technology. This allows users to manually store the locations where police frequently monitor traffic, with the detector sounding an alarm when approaching that location in the future (this is accomplished by pushing a button and doesn't require coordinates to be entered). These detectors also allow users to manually store the coordinates of sites of frequent false alarms, which the GPS enabled detector will then ignore. Some GPS enabled detectors can download the GPS coordinates of speed monitoring cameras and redlight cameras from the internet, which are contained in the Trinity database. A traveler from out of state, passing through Arizona for example, would receive an alarm when approaching the location of a speed monitoring camera.
he superheterodyne receiver in radar detectors have a local oscillator that radiates slightly, so it is possible to build a radar-detector detector, which detects such emissions (usually the frequency of the radar type being detected, plus about 10 MHz). The VG-2 Interceptor was the first device developed for this purpose, but has since been eclipsed by the Spectre III.  This form of "electronic warfare" cuts both ways - since detector-detectors use a similar superheterodyne receiver, many early "stealth" radar detectors were equipped with a radar-detector-detector-detector circuit, which shuts down the main radar receiver when the detector-detector's signal is sensed, thus preventing detection by such equipment. This technique borrows from ELINT surveillance countermeasures. In the early 1990s, BEL-Tronics, Inc. of Ontario, Canada (where radar detector use is prohibited) found that the local oscillator frequency of the detector could be altered to be out of the range of the VG-2 Interceptor. This resulted in detector manufacturers responding by changing their local oscillator frequency. Today, practically every radar detector on the market is immune to the VG-2 Interceptor.